Near-infrared reflecting copper oxide-coated particles

Abstract

This invention relates to copper oxide-coated particles with near-infrared reflectivity. The copper oxide-coated pigment comprises particles having an outer surface and a copper oxide layer on said outer surface. The pigment has a reflectance of less than or equal to 5% for electromagnetic radiation in the visible spectrum and a reflectance of greater than or equal to 5% for electromagnetic radiation in the near-infrared and lidar spectra. The particles are cobalt oxide or carbon black. A method for forming the copper oxide-coated particles includes combining a precipitant with a solution of copper nitrate and particles to form coated particles. The particles are cobalt oxide or carbon black. The particles are washed to obtain washed coated particles, and the washed coated particles are filtered to obtain filtered coated particles. The filtered coated particles are dried to obtain dried coated particles, and the dried coated particles are calcined to form copper oxide-coated particles.

Description

Technical Field

[0001] The present invention generally relates to particles that reflect near-infrared electromagnetic radiation, and more particularly to copper oxide coated particles that reflect near-infrared electromagnetic radiation. Background Technology

[0002] For obstacle detection and avoidance systems for autonomous vehicles, LiDAR systems using pulsed laser electromagnetic radiation with wavelengths of 905 nanometers (nm) or 1050 nm have been proposed and tested. However, dark pigments (e.g., black) used in coating systems to provide deep colors not only absorb visible electromagnetic radiation (which darkens the color) but also absorb near-infrared electromagnetic radiation with wavelengths greater than approximately 750 nm (which includes LiDAR electromagnetic radiation).

[0003] Therefore, there is a need for alternative deep-coloring pigments that absorb electromagnetic radiation in the visible spectrum but reflect near-infrared electromagnetic radiation with wavelengths of approximately 905 nm or 1050 nm. Summary of the Invention

[0004] The first aspect includes a copper oxide-coated pigment comprising: particles having an outer surface; and a copper oxide layer on the outer surface of the particles, wherein the copper oxide-coated pigment has a reflectance of less than or equal to 5% for electromagnetic radiation in the visible spectrum, and the copper oxide-coated pigment has a reflectance of greater than or equal to 5% for electromagnetic radiation in the near-infrared and lidar spectra, and the particles are selected from cobalt oxide (Co3O4) or carbon black.

[0005] The second aspect includes a pigment coated with copper oxide according to the first aspect, wherein the particles are cobalt oxide (Co3O4).

[0006] The third aspect includes a pigment coated with copper oxide according to the first aspect, wherein the particles are carbon black.

[0007] The fourth aspect includes a copper oxide-coated pigment from any one of the first to third aspects, wherein the copper oxide-coated pigment has a reflectance of less than or equal to 2% for electromagnetic radiation in the visible spectrum.

[0008] The fifth aspect includes a copper oxide-coated pigment from any of the first to fourth aspects, wherein the copper oxide-coated pigment has a reflectivity of greater than or equal to 20% for electromagnetic radiation in the near-infrared and lidar spectra.

[0009] The sixth aspect includes a copper oxide-coated pigment from any of the first to fifth aspects, wherein the copper oxide-coated pigment has a reflectance of greater than or equal to 0.5% and less than or equal to 2% for electromagnetic radiation in the visible spectrum.

[0010] The seventh aspect includes a copper oxide-coated pigment from any of the first to sixth aspects, wherein the copper oxide-coated pigment has a reflectivity of greater than or equal to 10% and less than or equal to 65% for electromagnetic radiation in the near-infrared and lidar spectra.

[0011] The eighth aspect includes a copper oxide-coated pigment from any of the first to seventh aspects, wherein the copper oxide-coated pigment has a blackness greater than or equal to 150 and less than or equal to 165.

[0012] The ninth aspect includes a coating comprising: a coating binder; and at least one pigment coated with a copper oxide according to any one of the first to eighth aspects.

[0013] The tenth aspect includes the coating of the ninth aspect, wherein the coating has a color with a brightness of less than or equal to 40 in the CIELAB color space.

[0014] The eleventh aspect includes a vehicle comprising a body panel coated with the paint of the ninth or tenth aspect.

[0015] The twelfth aspect includes a method for forming copper oxide-coated particles, comprising: combining a precipitant with a solution containing copper nitrate and particles to form coated particles, wherein the particles are cobalt oxide (Co3O4) or carbon black; washing the particles to obtain washed coated particles; filtering the washed coated particles to obtain filtered coated particles; drying the filtered coated particles to obtain dried coated particles; and calcining the dried coated particles to form copper oxide-coated particles.

[0016] The thirteenth aspect includes the method of the twelfth aspect, wherein the precipitant is selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate.

[0017] The fourteenth aspect includes the method of the twelfth or thirteenth aspect, wherein the precipitant is ammonium carbonate.

[0018] The fifteenth aspect includes the method of any one of aspects 12 to 14, wherein the particles are cobalt oxide (Co3O4).

[0019] The sixteenth aspect includes the method of any one of aspects twelve to fifteen, wherein the particles are carbon black particles.

[0020] The seventeenth aspect includes the method of any one of aspects twelve to sixteen, wherein the coated particles include particles coated with copper nitrate, particles coated with copper hydroxide, or particles coated with copper carbonate.

[0021] The eighteenth aspect includes the method of any one of aspects twelve to seventeen, wherein washing the coated particles comprises washing the coated particles in a mixture of ethanol and water.

[0022] The nineteenth aspect includes the method of the fifteenth aspect, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0023] The twentieth aspect includes the method of the nineteenth aspect, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature greater than or equal to 430°C and less than or equal to 470°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0024] The twenty-first aspect includes the method of the sixteenth aspect, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 5 hours and less than or equal to 15 hours.

[0025] The twenty-second aspect includes the method of the twenty-first aspect, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature greater than or equal to 200°C and less than or equal to 300°C for a duration greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0026] The twenty-third aspect includes a method for forming copper oxide-coated cobalt oxide particles, comprising: combining a sodium carbonate precipitant with a solution containing copper nitrate and cobalt nitrate to form coated cobalt oxide particles; washing the coated cobalt oxide particles to obtain washed coated cobalt oxide particles; filtering the washed coated cobalt oxide particles to obtain filtered coated cobalt oxide particles; drying the filtered coated cobalt oxide particles to obtain dried coated cobalt oxide particles; and calcining the dried coated cobalt oxide particles to form copper oxide-coated cobalt oxide particles.

[0027] The twenty-fourth aspect includes the method of the twenty-third aspect, wherein the coated cobalt oxide particles comprise cobalt oxide coated with copper nitrate.

[0028] The twenty-fifth aspect includes the method of the twenty-third or twenty-fourth aspect, wherein drying the filtered coated cobalt oxide particles comprises drying the filtered coated cobalt oxide particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0029] The twenty-sixth aspect includes a method comprising any one of the twenty-third to twenty-fifth aspects, wherein calcining the dried coated cobalt oxide particles comprises calcining the dried coated cobalt oxide particles at a temperature greater than or equal to 430°C and less than or equal to 470°C for a duration greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0030] The contents and additional features provided by the embodiments described herein will be more fully understood in light of the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0031] The embodiments illustrated in the accompanying drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which similar structures are indicated by similar reference numerals, wherein:

[0032] Figure 1A The reflectivity of conventional colorants versus the wavelength of electromagnetic radiation is depicted graphically.

[0033] Figure 1B The reflectivity of the colorant in relation to the wavelength of electromagnetic radiation according to the embodiments disclosed and described herein is graphically depicted.

[0034] Figure 2 A bar graph depicting the blackness of commercially available materials and black TiO2;

[0035] Figure 3 A system comprising copper oxide-coated cobalt oxide particles according to embodiments disclosed and described herein is schematically depicted;

[0036] Figure 4A A bar graph illustrating the blackness of various materials containing a copper oxide-coated cobalt oxide prior to the application of a transparent coating, according to embodiments disclosed and described herein;

[0037] Figure 4B A bar graph illustrating the blackness of various materials containing copper oxide-coated carbon black after the application of a transparent coating, according to embodiments disclosed and described herein;

[0038] Figure 5 The image is taken with an infrared detection camera, showing the reflection of electromagnetic radiation in the near-infrared and lidar spectra of a copper oxide-coated cobalt oxide according to the embodiments disclosed and described herein.

[0039] Figure 6A vehicle with side panels is schematically depicted, the side panels being coated with a dark-colored paint for a reflective lidar according to one or more embodiments disclosed and described herein;

[0040] Figure 7 The schematic depiction is painted with Figure 5 A cross-sectional view of the side panel of the reflective lidar with a dark-colored coating;

[0041] Figure 8 A bar graph showing the blackness of panels with various pigments before the application of a clear coating;

[0042] Figure 9 A bar graph showing the blackness of panels with various pigments after a clear coating has been applied;

[0043] Figure 10 Line graph showing the reflectivity of panels with various pigments after a transparent coating has been applied;

[0044] Figure 11 A bar graph showing the lidar intensity of panels with various pigments after a transparent coating has been applied;

[0045] Figures 12A to 12C To illustrate SEM images of copper oxide-coated carbon black according to embodiments disclosed and described herein; and

[0046] Figure 13 A bar graph showing the lidar intensity of panels with various pigments after a transparent coating has been applied. Detailed Implementation

[0047] According to one or more embodiments described herein, a copper oxide-coated cobalt oxide pigment comprises: cobalt oxide particles having an outer surface; and a copper oxide layer on the outer surface of the cobalt oxide particles, wherein the copper oxide-coated cobalt oxide pigment has a reflectance of less than or equal to 5% for electromagnetic radiation in the visible spectrum, and has a reflectance of greater than or equal to 5% for electromagnetic radiation in the near-infrared and lidar spectra.

[0048] According to one or more embodiments described herein, a copper oxide-coated carbon black pigment comprises: carbon black particles having an outer surface; and a copper oxide layer on the outer surface of the carbon black particles, wherein the copper oxide-coated carbon black pigment has a reflectance of less than or equal to 5% for electromagnetic radiation in the visible spectrum, and has a reflectance of greater than or equal to 5% for electromagnetic radiation in the near-infrared and lidar spectra.

[0049] Therefore, the copper oxide-coated particles disclosed and described herein exhibit a dark color and reflect near-infrared electromagnetic radiation, including lidar, with wavelengths between 850 nm and 1550 nm (inclusive). In embodiments, the copper oxide-coated particles disclosed and described herein can be incorporated into coating systems to form dark-colored coatings that reflect near-infrared and lidar radiation, which can be used in any application using conventional coatings. For example, the coating systems disclosed and described herein can be used to coat parts of vehicles, buildings, roads, traffic signs, or any other objects, enabling near-infrared and lidar detection systems to detect articles coated with dark-colored coatings that reflect near-infrared and lidar radiation. In embodiments, the copper oxide-coated particles disclosed and described herein can be used in black-colored coatings, or the copper oxide-coated particles can be used with other pigments or colorants in coatings of any color.

[0050] As used herein, the term “near-infrared electromagnetic radiation” refers to electromagnetic radiation with wavelengths between 750 nm and 950 nm (inclusive), and “lidar” refers to electromagnetic radiation with wavelengths between 905 nm and 1550 nm (inclusive).

[0051] As used herein, the term "visible spectrum" refers to electromagnetic radiation with wavelengths between 350 nm and 750 nm (inclusive).

[0052] The coating for reflective lidar can be applied to a surface to provide a colored surface for reflective lidar. The surface color can be black, but it can also be any other color by combining the copper oxide-coated particles disclosed and described herein with other pigments and colorants. Non-limiting examples of the application of the coating disclosed and described herein include surfaces of vehicle body panels, such as door panels, vehicle quarter panels, etc., as well as surfaces of buildings, roads, traffic signs, and other surfaces where near-infrared or lidar reflection is desired. The use of copper oxide-coated particles for reflective lidar allows for the detection of vehicles, even dark-colored vehicles, or other surfaces to be detected by lidar systems. Various embodiments of copper oxide-coated C particles for reflective lidar, and methods of their manufacture and use, will be described in further detail herein with specific reference to the accompanying drawings.

[0053] One difficulty in forming dark-colored (such as black) particles and coating systems containing dark-colored particles that reflect lidar or near-infrared electromagnetic radiation is that the electromagnetic radiation in the visible spectrum and near-infrared electromagnetic radiation or lidar are very close. Materials that provide dark colors such as black do not reflect electromagnetic radiation within the visible spectrum. Such materials generally also do not reflect electromagnetic radiation, such as near-infrared and lidar, just outside the visible spectrum. Carbon black is such a material, commonly used as a dark pigment, which does not reflect electromagnetic radiation in the visible spectrum, nor does it reflect near-infrared or lidar electromagnetic radiation. Therefore, materials that do not reflect electromagnetic radiation within the visible spectrum but reflect near-infrared or lidar electromagnetic radiation, just outside the visible spectrum, have a sharply increased reflectivity.

[0054] Now for reference Figure 1A This shows the reflectance of materials commonly used as colorants in coating systems. Along... Figure 1A The y-axis represents the percentage of reflectivity, along which... Figure 1A The x-axis provides the wavelength of electromagnetic radiation. The reflectance of conventional black colorants such as carbon black is shown along the bottom of the graph. Figure 1A As shown, carbon black colorants do not reflect electromagnetic radiation in the visible spectrum (left side of the figure). Figure 1A As shown, the reflectance of this black colorant is close to 0% within the visible spectrum of electromagnetic radiation. This indicates that the colorant provides a dark, near-pure black color. However, this conventional colorant also reflects approximately 0% of electromagnetic radiation outside the visible spectrum (right side of the figure), such as near-infrared electromagnetic radiation or lidar electromagnetic radiation (e.g., from greater than about 750 nanometers (nm) to about 1550 nm). Similarly, the reflectance of white TiO2 used as a conventional white colorant is shown near the top of the figure. Figure 1A As shown, white TiO2 reflects near-infrared and lidar electromagnetic radiation, as indicated on the right side of the figure (e.g., from greater than about 750 nm to 1550 nm), where the reflection of near-infrared and lidar electromagnetic radiation is greater than 40% at 1550 nm and about 60% at 905 nm. However, white TiO2, as its name suggests, also reflects electromagnetic radiation in the visible spectrum. Figure 1A As shown, white TiO2 reflects nearly 80% of electromagnetic radiation in the visible spectrum. Therefore, these colorants—carbon black or white TiO2—are not suitable as dark-colored particles that also reflect near-infrared or lidar electromagnetic radiation.

[0055] Figure 1B A diagram illustrating target conditions for particles that do not reflect light in the visible spectrum of electromagnetic radiation but reflect near-infrared and lidar electromagnetic radiation. Figure 1BIn the figure, the percentage of reflectance is measured along the y-axis, and the wavelength of electromagnetic radiation is provided along the x-axis. The reflectance of a standard black colorant is shown along the bottom of the graph, which is compared with... Figure 1A The reflectivity is the same as that of conventional black colorants (such as carbon black). Figure 1B As shown, particles that do not reflect electromagnetic radiation in the visible spectrum but reflect near-infrared and lidar electromagnetic radiation have at least two distinct reflection regions. The first reflection region is within the visible spectrum of electromagnetic radiation. Figure 1B The left side of the diagram is marked "1". In this reflective region, particles that do not reflect electromagnetic radiation in the visible spectrum but reflect near-infrared and lidar electromagnetic radiation behave the same as conventional black colorants (such as carbon black) through electromagnetic radiation that does not reflect the visible spectrum. Figure 1B As shown, particles that do not reflect electromagnetic radiation in the visible spectrum but reflect near-infrared and lidar electromagnetic radiation reflect almost 0% of electromagnetic radiation in the visible spectrum, but these particles have a second reflection region outside the visible spectrum of electromagnetic radiation.

[0056] The second reflection region includes electromagnetic radiation (including near-infrared and lidar electromagnetic radiation) with wavelengths between 750 nm and 1050 nm (inclusive). Particles that do not reflect electromagnetic radiation in the visible spectrum but do reflect near-infrared and lidar electromagnetic radiation in this second reflection region appear similar to white TiO2 by reflecting a large amount of electromagnetic radiation within it. Figure 1B As shown, particles that do not reflect electromagnetic radiation in the visible spectrum but reflect near-infrared and lidar electromagnetic radiation reflect, for example, about 60% of lidar electromagnetic radiation with a wavelength of 905 nm and more than 40% of lidar electromagnetic radiation with a wavelength of 1550 nm. By having a reflectivity similar to that of white TiO2 in the second reflection region, the particles are able to reflect a sufficient amount of near-infrared and lidar electromagnetic radiation that can be detected by the lidar system.

[0057] Figure 1B This demonstrates the difficulty in forming particles that do not reflect electromagnetic radiation in the visible spectrum but do reflect near-infrared and lidar electromagnetic radiation. In particular, Figure 1B This illustrates a sharp increase in reflectance just outside the visible spectrum of electromagnetic radiation. In this embodiment, this sharp increase in reflectance occurs at the wavelength of electromagnetic radiation at 905 nm or approximately 905 nm, which is the wavelength of electromagnetic radiation commonly used in lidar systems. Figure 1BAs shown, the reflectance increases from approximately 0% to nearly 60% at the wavelength of electromagnetic radiation at approximately 905 nm. Forming particles with such a precise and dramatic increase in reflectance is difficult to achieve and has a very small margin of error. For example, if a material reflects too much electromagnetic radiation within the visible spectrum, the color will not appear pure black, but will have, for example, a small amount of red or purple. However, if the material does not reflect a sufficient amount of near-infrared or lidar electromagnetic radiation, it will be unsuitable for detection by lidar systems.

[0058] Some materials do not reflect most of the visible spectrum of electromagnetic radiation but do reflect near-infrared and lidar electromagnetic radiation; however, these materials cannot reproduce the visible appearance of carbon black (i.e., they have approximately 0% reflectivity for electromagnetic radiation in the visible spectrum). One such material that has attracted attention is ferrochrome oxide and its derivatives. Although ferrochrome oxide materials generally reflect near-infrared and lidar electromagnetic radiation, colorants made from ferrochrome oxide materials are often called "cool black" because they contain trace amounts of red or blue. Figure 2 A bar graph showing the emissivity of various materials along the y-axis is presented. Emissivity was measured using an X-Rite spectrophotometer. Figure 2 On the far left is carbon black, a material commonly used as a black colorant, but carbon black does not reflect near-infrared or lidar electromagnetic radiation. For example... Figure 2 As shown, carbon black has a blackness of approximately 165. Materials 1-7 are chromium iron oxide-containing materials that reflect near-infrared and lidar electromagnetic radiation; however, from... Figure 2 As can be seen, these materials have a blackness of approximately 142 or less. This difference in blackness is significant because materials 1-7 have a slight red or blue tint. This considerable difference in blackness between carbon black and materials 1-7 indicates that materials 1-7 are generally unsuitable for use in applications requiring pure black, such as in paints, and in paints used in automobiles.

[0059] Another material of interest for black color applications is copper(II) oxide or copper oxide (CuO). CuO is a common inorganic compound that is a black solid in its natural state. However, not all copper oxides possess this black color. That is, another stable oxide of copper is cuprous oxide (Cu₂O), which is a red solid in its natural state. Therefore, the oxidation state of copper is important for ensuring the material has a black color. CuO is a product of copper mining and a precursor to many other copper-containing products and chemical compounds. In some applications, such as ceramics and glazes, CuO has been used as a black pigment. However, CuO does not reflect near-infrared or lidar electromagnetic radiation. That is, CuO in its natural state behaves very much like carbon black because it does not reflect electromagnetic radiation in the visible spectrum, nor does it reflect electromagnetic radiation in the near-infrared or lidar spectra. Unbound from any particular theory, CuO has a band gap of 2.0 eV, and as described in more detail below, it does not readily reflect electromagnetic radiation in the near-infrared or lidar spectra. When CuO is manipulated to give it a band gap that is more suitable for reflecting electromagnetic radiation in the near-infrared or lidar spectrum, its color fades to brownish-black, making it unsuitable for some applications, such as in coatings, especially automotive coatings.

[0060] A band gap generally refers to the energy difference (in electron volts or eV) between the top of the valence band (VB) and the bottom of the conduction band (CB). The VB is the band from which electrons, when excited, can jump and move into electron orbitals within the CB. The VB is the outermost electron orbital of an atom that an electron can actually occupy. The band gap is the energy required for an electron to move from the VB to the CB and can indicate the electrical conductivity of a material. In optical devices, the band gap is related to the threshold at which photons can be absorbed by a material. Therefore, the band gap determines which portion of the electromagnetic spectrum a material can absorb. Generally, materials with large band gaps absorb more of the electromagnetic spectrum with shorter wavelengths, while materials with small band gaps absorb more of the electromagnetic spectrum with longer wavelengths. In other words, a larger band gap means that a large amount of energy is required to excite valence electrons into the CB. Conversely, when the valence and conduction bands overlap, as they are in metals, electrons can easily jump between the two bands, meaning the material has high conductivity. However, it has been found that by manipulating the band gap of a material, the type of electromagnetic spectrum absorbed by the material can be controlled.

[0061] Generally, a band gap of 1.5 eV to 1.8 eV is required for a compound to absorb (i.e., not reflect) electromagnetic radiation in the visible spectrum and reflect electromagnetic radiation in the near-infrared and lidar spectra. Bulk CuO, without manipulation, does not meet these requirements. Bulk CuO has been reported to have a band gap of 2.0 eV and an emissivity of 120. This band gap, outside the 1.5 eV to 1.8 eV range, is considered to reflect electromagnetic radiation in the near-infrared and lidar spectra. Furthermore, as referenced above… Figure 2The blackness of CuO is 120, which is significantly lower than that of carbon black (170). Therefore, in the embodiments disclosed and described herein, CuO is manipulated by reducing the particle size of CuO to decrease the band gap of CuO and increase the blackness of CuO.

[0062] As mentioned above, bulk CuO is unsuitable as a colorant that absorbs (i.e., does not reflect) electromagnetic radiation in the visible spectrum and reflects electromagnetic radiation in the near-infrared or lidar spectrum, as indicated by its band gap of approximately 2.0 eV. However, according to embodiments disclosed and described herein, reducing the size of CuO particles results in a reduced band gap and increased blackness of the CuO particles. According to embodiments, bulk CuO particles are reduced to nanoscale particles (also referred to herein as “nanoparticles”). This size reduction of bulk CuO particles can be achieved by any suitable method, such as grinding, ball milling, jet milling, etc. In the implementation, the size of the bulk CuO particles is reduced to a crystal size of less than or equal to 100 nm, such as less than or equal to 95 nm, less than or equal to 90 nm, less than or equal to 85 nm, less than or equal to 80 nm, less than or equal to 75 nm, less than or equal to 70 nm, less than or equal to 65 nm, less than or equal to 60 nm, less than or equal to 55 nm, less than or equal to 50 nm, less than or equal to 45 nm, less than or equal to 40 nm, less than or equal to 35 nm, less than or equal to 30 nm, less than or equal to 25 nm, less than or equal to 20 nm, less than or equal to 15 nm, or less than or equal to 10 nm.

[0063] In the implementation, the size of the bulk CuO particles is reduced to an average particle size of less than or equal to 60 nm and greater than or equal to 10 nm, such as less than or equal to 55 nm and greater than or equal to 10 nm, less than or equal to 50 nm and greater than or equal to 10 nm, less than or equal to 45 nm and greater than or equal to 10 nm, less than or equal to 40 nm and greater than or equal to 10 nm, less than or equal to 35 nm and greater than or equal to 10 nm, less than or equal to 30 nm and greater than or equal to 10 nm, less than or equal to 25 nm and greater than or equal to 10 nm, less than or equal to 20 nm and greater than or equal to 10 nm, less than or equal to 15 nm and greater than or equal to 10 nm, less than or equal to 60 nm and greater than or equal to 15 nm. m, such as less than or equal to 55nm and greater than or equal to 15nm, less than or equal to 50nm and greater than or equal to 15nm, less than or equal to 45nm and greater than or equal to 15nm, less than or equal to 40nm and greater than or equal to 15nm, less than or equal to 35nm and greater than or equal to 15nm, less than or equal to 30nm and greater than or equal to 15nm, less than or equal to 25nm and greater than or equal to 15nm, less than or equal to 20nm and greater than or equal to 15nm, less than or equal to 60nm and greater than or equal to 20nm, less than or equal to 55nm and greater than or equal to 20nm, less than or equal to 50nm and greater than or equal to 20nm, less than or equal to 45nm and greater than or equal to 20nm, less than or equal to 20nm, etc. The following are the ranges: 40nm and greater than or equal to 20nm, 35nm and greater than or equal to 20nm, 30nm and greater than or equal to 20nm, 25nm and greater than or equal to 20nm, 60nm and greater than or equal to 25nm, 55nm and greater than or equal to 25nm, 50nm and greater than or equal to 25nm, 45nm and greater than or equal to 25nm, 40nm and greater than or equal to 25nm, 35nm and greater than or equal to 25nm, 30nm and greater than or equal to 25nm, 60nm and greater than or equal to 30nm, and 55nm and greater than or equal to 20nm. Or equal to 30nm, less than or equal to 50nm and greater than or equal to 30nm, less than or equal to 45nm and greater than or equal to 30nm, less than or equal to 40nm and greater than or equal to 30nm, less than or equal to 35nm and greater than or equal to 30nm, less than or equal to 60nm and greater than or equal to 35nm, less than or equal to 55nm and greater than or equal to 35nm, less than or equal to 50nm and greater than or equal to 35nm, less than or equal to 45nm and greater than or equal to 35nm, less than or equal to 40nm and greater than or equal to 35nm, less than or equal to 60nm and greater than or equal to 40nm, less than or equal to 55nm and greater than or equal to 40nm, less than or equal to 50nm and greater than or equal to 40nmBulk CuO particles with dimensions reduced to nanoparticle size are referred to as "CuO nanoparticles" in this paper. These nanoparticles have dimensions less than or equal to 45 nm and greater than or equal to 40 nm, less than or equal to 60 nm and greater than or equal to 45 nm, less than or equal to 55 nm and greater than or equal to 45 nm, less than or equal to 50 nm and greater than or equal to 50 nm, less than or equal to 55 nm and greater than or equal to 50 nm, or less than or equal to 60 nm and greater than or equal to 55 nm.

[0064] The band gap of CuO is reduced by decreasing the size of bulk CuO particles to, for example, the average particle size disclosed herein. In embodiments, the band gap of CuO nanoparticles, measured by X-ray photoelectron spectroscopy (XPS), is greater than or equal to 1.6 eV and less than or equal to 1.9 eV, such as greater than or equal to 1.6 eV and less than or equal to 1.8 eV, greater than or equal to 1.6 eV and less than or equal to 1.7 eV, greater than or equal to 1.7 eV and less than or equal to 1.9 eV, greater than or equal to 1.7 eV and less than or equal to 1.8 eV, greater than or equal to 1.7 eV and less than or equal to 1.8 eV, or greater than or equal to 1.8 eV and less than or equal to 1.9 eV. Without being bound by any particular theory, it is considered that the band gap of CuO nanoparticles is reduced by surface defects caused by reducing bulk CuO to CuO nanoparticles compared to the band gap of bulk CuO particles. Furthermore, it is believed that the smaller the average crystal size of CuO nanoparticles, the lower the band gap of CuO nanoparticles. Therefore, by reducing bulk CuO particles to CuO nanoparticles according to the embodiments disclosed and described herein, the band gap of the CuO nanoparticles is within the range of electromagnetic radiation reflected in the near-infrared and lidar spectra, such as a band gap between 1.5 eV and 2.0 eV or between 1.5 eV and 1.8 eV.

[0065] The blackness (i.e., the measure of blackness) increases as the size of the bulk CuO decreases. Therefore, in embodiments, the blackness of the CuO nanoparticles is greater than or equal to 130 and less than or equal to 145, such as greater than or equal to 133 and less than or equal to 145, greater than or equal to 135 and less than or equal to 145, greater than or equal to 138 and less than or equal to 145, greater than or equal to 140 and less than or equal to 145, greater than or equal to 143 and less than or equal to 145, greater than or equal to 130 and less than or equal to 143, greater than or equal to 133 and less than or equal to 143, greater than or equal to 135 and less than or equal to 143, greater than or equal to 138 and less than or equal to 145. 3. Greater than or equal to 140 and less than or equal to 143, greater than or equal to 130 and less than or equal to 140, greater than or equal to 133 and less than or equal to 140, greater than or equal to 135 and less than or equal to 140, greater than or equal to 138 and less than or equal to 140, greater than or equal to 130 and less than or equal to 138, greater than or equal to 133 and less than or equal to 138, greater than or equal to 135 and less than or equal to 138, greater than or equal to 130 and less than or equal to 135, greater than or equal to 133 and less than or equal to 135, or greater than or equal to 130 and less than or equal to 133. Even by reducing the particle size of bulk CuO to increase blackness, the blackness of CuO nanoparticles is lower than that required for some applications, such as coatings, especially automotive coatings.

[0066] According to the embodiments disclosed and described herein, the low blackness of CuO nanoparticles (compared to the blackness of carbon black, which is 170) is addressed by depositing a CuO layer on the surface of particles with a blackness greater than that of CuO nanoparticles. According to the embodiments, CuO is deposited on carbon black or cobalt oxide (Co3O4) particles to improve blackness. As mentioned above, carbon black has very high blackness. Co3O4 particles are also known to have high blackness, such as blackness greater than that of CuO nanoparticles.

[0067] Reference Figure 3 The effects of a system having a CuO layer coated on carbon black or Co3O4 particles are described. The copper oxide-coated particle system 300 includes copper oxide-coated particles 310, which contain carbon black or Co3O4 particles 311 coated with a CuO layer 312. For example... Figure 3 As shown, according to the embodiment, a CuO layer 312 is deposited on the outer surface of larger carbon black or Co3O4 particles 311 with a particle size greater than or equal to 1 μm and less than or equal to 10 μm. Figure 3As shown, the copper oxide-coated particles 310 can be suspended in a transparent carrier 330, which is not limited and can be any suitable carrier for the desired application. The carrier 330 will be described in more detail below. Electromagnetic radiation in the visible spectrum 340 and electromagnetic radiation in the near-infrared and lidar spectra 350 incident on the copper oxide-coated particle system 300 both enter the copper oxide-coated particle system 300 and pass through the transparent carrier 330, where they are incident on the copper oxide-coated particles 310. A portion of the electromagnetic radiation in the visible spectrum 340 is absorbed by the copper oxide 312, and a portion of the electromagnetic radiation in the visible spectrum 340 passes through the copper oxide 312 and is incident on the carbon black or cobalt oxide particles 311. A portion of the electromagnetic radiation in the visible spectrum 340 incident on the carbon black or cobalt oxide particles 311 is absorbed by the carbon black or cobalt oxide particles 311, such that almost no electromagnetic radiation in the visible spectrum 340 is reflected out of the copper oxide-coated particle system 300.

[0068] Electromagnetic radiation in the near-infrared and lidar spectra 350 incident on the copper oxide-coated particles 310 is reflected by the copper oxide 312, causing most of the electromagnetic radiation in the near-infrared and lidar spectra 350 to be reflected out of the copper oxide-coated particle system 300. Any electromagnetic radiation in the near-infrared and lidar spectra 350 that is not reflected by the copper oxide 312 is absorbed by the carbon black or cobalt oxide particles 311.

[0069] There is an inverse relationship between the amount of copper oxide 312 on the copper oxide-coated particles 310 and the blackness of the copper oxide-coated particles 310. In other words, the lower the content of copper oxide 312 in the copper oxide-coated particles 310, the higher the blackness. However, there is a direct relationship between the amount of copper oxide 312 in the copper oxide-coated particles 310 and the reflectance of electromagnetic radiation in the near-infrared and lidar spectra. In other words, the greater the amount of copper oxide 312 in the copper oxide-coated particles 310, the more electromagnetic radiation is reflected in the near-infrared and lidar spectra. Therefore, the embodiment of the copper oxide-coated particles 310 achieves a balance between the amount of copper oxide 312 and carbon black or cobalt oxide 311.

[0070] In an embodiment, the copper oxide-coated particles 310 may include copper oxide 312, wherein, based on the total weight of the copper oxide-coated particles 310, the amount of copper oxide 312 is greater than or equal to 1.0 wt% and less than or equal to 90.0 wt%, such as greater than or equal to 10.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 60.0 wt% and less than or equal to 90.0 wt%, etc. 70.0 wt% or less than or equal to 90.0 wt%, 80.0 wt% or more than or equal to 90.0 wt%, 1.0 wt% or more than or equal to 80.0 wt%, 10.0 wt% or more than or equal to 80.0 wt%, 20.0 wt% or more than or equal to 80.0 wt%, 30.0 wt% or more than or equal to 80.0 wt%, 40.0 wt% or more than or equal to 80.0 wt%, 50.0 wt% or more than or equal to 80.0 wt%, 60.0 wt% or more than or equal to 80.0 wt%, 7 ... 80.0 wt%, greater than or equal to 25.0 wt% and less than or equal to 75.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 60.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 1 0.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 60.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 50.0 wt%.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 30.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 30.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 30.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 20.0 wt%, greater than or equal to 1.0 wt% and less than or equal to 10.0 wt%.

[0071] In an embodiment, the copper oxide-coated particles 310 may contain carbon black or cobalt oxide 311, wherein, based on the total weight of the copper oxide-coated particles 310, the amount of carbon black or cobalt oxide 311 is greater than or equal to 10.0 wt% and less than or equal to 99.0 wt%, such as greater than or equal to 20.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 60.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 70.0 wt% and less than or equal to 99.0 wt%. %, greater than or equal to 80.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 90.0 wt% and less than or equal to 99.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 60.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 70.0 wt% and less than or equal to 90.0 wt%, greater than or equal to 80.0 wt% and less than or equal to 90.0 wt%, ...90.0 wt%, less than or equal to 90.0 wt%, less than or equal to 90.0 wt%, greater than or equal to 80.0 wt%, less than or equal to 90.0 wt%, less 90.0 wt% or more, greater than or equal to 10.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 50.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 60.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 70.0 wt% and less than or equal to 80.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 70.0 wt%, greater than or equal to 9 ... The following concentrations are specified: 30.0 wt% and less than or equal to 70.0 wt%; greater than or equal to 40.0 wt% and less than or equal to 70.0 wt%; greater than or equal to 50.0 wt% and less than or equal to 70.0 wt%; greater than or equal to 60.0 wt% and less than or equal to 70.0 wt%; greater than or equal to 10.0 wt% and less than or equal to 60.0 wt%; greater than or equal to 20.0 wt% and less than or equal to 60.0 wt%; greater than or equal to 30.0 wt% and less than or equal to 60.0 wt%; greater than or equal to 40.0 wt% and less than or equal to 60.0 wt%; greater than or equal to 50.0 wt% and less than or equal to 60.0 wt%; greater than or equal to 10.0 wt% and less than or equal to 50.0 wt%.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 40.0 wt% and less than or equal to 50.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 20.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 30.0 wt% and less than or equal to 40.0 wt%, greater than or equal to 10.0 wt% and less than or equal to 30.0 wt%, greater than or equal to 20.0 wt%, or greater than or equal to 10.0 wt% and less than or equal to 20.0 wt%.

[0072] According to the implementation plan, before applying the transparent coating, the blackness of the copper oxide-coated particles 310 is greater than or equal to 150 and less than or equal to 165, such as greater than or equal to 152 and less than or equal to 165, greater than or equal to 155 and less than or equal to 165, greater than or equal to 158 and less than or equal to 165, greater than or equal to 160 and less than or equal to 165, greater than or equal to 162 and less than or equal to 165, greater than or equal to 150 and less than or equal to 162, greater than or equal to 152 and less than or equal to 162, greater than or equal to 155 and less than or equal to 162, greater than or equal to 158 and less than Or equal to 162, greater than or equal to 160 and less than or equal to 162, greater than or equal to 150 and less than or equal to 160, greater than or equal to 152 and less than or equal to 160, greater than or equal to 155 and less than or equal to 160, greater than or equal to 158 and less than or equal to 160, greater than or equal to 150 and less than or equal to 158, greater than or equal to 152 and less than or equal to 158, greater than or equal to 155 and less than or equal to 158, greater than or equal to 150 and less than or equal to 155, greater than or equal to 152 and less than or equal to 155, or greater than or equal to 150 and less than or equal to 152.

[0073] Before applying the transparent coating, the blackness of the copper oxide-coated cobalt oxide embodiment compared to other materials is shown in... Figure 4A .from Figure 4A As can be seen, the standard (STD), carbon black, and uncoated cobalt oxide (Co3O4) all have a blackness of approximately 165; this is the pigment standard used in true black applications, such as general-purpose coatings, and especially in automotive coatings. Figure 4A The results show that the blackness of cool black (a chromium-based pigment commonly used in applications), bulk CuO, and CuO nanoparticles (nano CuO) is far lower than that of pigment standards used in true black applications. However, copper oxide-coated cobalt oxide (CuO-Co3O4) has a blackness similar to that of pigment standards used in true black applications, such as those generally used in coatings, particularly automotive coatings.

[0074] After applying a transparent coating to the sample, the blackness of the copper oxide-coated carbon black embodiment compared to other materials is shown in the figure. Figure 4B .from Figure 4B As can be seen, carbon black has a blackness of approximately 135; this is the pigment standard used in true black applications, such as general-purpose coatings, especially in automotive coatings. Figure 4B The blackness of cold black (a chromium-based pigment commonly used in applications), bulk (commercial) CuO and CuO nanoparticles (nano CuO), a 50:50 mixture of CuO and carbon black, and a 25:75 mixture of CuO and carbon black are all significantly lower than the pigment standards used in true black applications. However, carbon black coated with copper oxide in a 50:50 ratio and carbon black coated with copper oxide in a 25:75 ratio have blackness similar to the pigment standards used in true black applications, such as those generally used in coatings, particularly automotive coatings.

[0075] Another method for measuring particle blackness is by its reflectance to electromagnetic radiation in the visible spectrum. According to the embodiment, using a UV-VIS-NIR spectrophotometer, the copper oxide-coated particles 310 have a reflectance to electromagnetic radiation in the visible spectrum of less than or equal to 5.0%, such as less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%, less than or equal to 1.5%, less than or equal to 1.0%, or less than or equal to 0.5%.In one or more embodiments, the copper oxide-coated particles have a reflectance to electromagnetic radiation in the visible spectrum that is greater than or equal to 0.5% and less than or equal to 5.0%, such as greater than or equal to 0.5% and less than or equal to 4.5%, greater than or equal to 0.5% and less than or equal to 4.0%, greater than or equal to 0.5% and less than or equal to 3.5%, greater than or equal to 0.5% and less than or equal to 3.0%, greater than or equal to 0.5% and less than or equal to 2.5%, greater than or equal to 0.5% and less than or equal to 2.0%, greater than or equal to 0.5% and less than or equal to 1.5%, greater than or equal to 0.5% and less than or equal to 1.0%, greater than or equal to 1.0% and less than or equal to 5.0%, etc. 5.0%, greater than or equal to 1.0% and less than or equal to 4.5%, greater than or equal to 1.0% and less than or equal to 4.0%, greater than or equal to 1.0% and less than or equal to 3.5%, greater than or equal to 1.0% and less than or equal to 3.0%, greater than or equal to 1.0% and less than or equal to 2.5%, greater than or equal to 1.0% and less than or equal to 2.0%, greater than or equal to 1.0% and less than or equal to 1.5%, greater than or equal to 1.5% and less than or equal to 5.0%, greater than or equal to 1.5% and less than or equal to 4.5%, greater than or equal to 1.5% and less than or equal to 4.0%, greater than or equal to 1.5% and less than or equal to 3.5%, greater than or equal to 1.5% and Less than or equal to 3.0%, greater than or equal to 1.5% and less than or equal to 2.5%, greater than or equal to 1.5% and less than or equal to 2.0%, greater than or equal to 2.0% and less than or equal to 5.0%, greater than or equal to 2.0% and less than or equal to 4.5%, greater than or equal to 2.0% and less than or equal to 4.0%, greater than or equal to 2.0% and less than or equal to 3.5%, greater than or equal to 2.0% and less than or equal to 3.0%, greater than or equal to 2.0% and less than or equal to 2.5%, greater than or equal to 2.5% and less than or equal to 5.0%, greater than or equal to 2.5% and less than or equal to 4.5%, greater than or equal to 2.5% and less than or equal to 4.0%, greater than or equal to 2 0.5% and less than or equal to 3.5%, greater than or equal to 2.5% and less than or equal to 3.0%, greater than or equal to 3.0% and less than or equal to 5.0%, greater than or equal to 3.0% and less than or equal to 4.5%, greater than or equal to 3.0% and less than or equal to 4.0%, greater than or equal to 3.0% and less than or equal to 3.5%, greater than or equal to 3.5% and less than or equal to 5.0%, greater than or equal to 3.5% and less than or equal to 4.5%, or greater than or equal to 4.5% and less than or equal to 5.0%.

[0076] In addition to absorbing electromagnetic radiation in the visible spectrum, the copper oxide-coated particles according to the embodiments disclosed and described herein also reflect electromagnetic radiation in the near-infrared and lidar spectra. According to one or more embodiments, the copper oxide-coated particles have a reflectivity of 5% or more for electromagnetic radiation in the near-infrared and lidar spectra, such as 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 60% or more, or 65% or more. In one or more embodiments, the copper oxide-coated particles have a reflectivity of greater than or equal to 5% and less than or equal to 65% for electromagnetic radiation in the near-infrared and lidar spectra, such as greater than or equal to 5% and less than or equal to 60%, greater than or equal to 5% and less than or equal to 55%, greater than or equal to 5% and less than or equal to 50%, greater than or equal to 5% and less than or equal to 45%, greater than or equal to 5% and less than or equal to 40%, greater than or equal to 5% and less than or equal to 35%, greater than or equal to 5% and less than or equal to 30%, greater than or equal to 5% and less than or equal to 25%, greater than or equal to 5% and less than or equal to 20%, greater than or equal to 5% and less than or equal to 15%, and greater than or equal to 5% and less than or equal to 10%. In one or more embodiments, the copper oxide-coated particles have a reflectivity of greater than or equal to 10% and less than or equal to 65% for electromagnetic radiation in the near-infrared and lidar spectra, such as greater than or equal to 10% and less than or equal to 60%, greater than or equal to 10% and less than or equal to 55%, greater than or equal to 10% and less than or equal to 50%, greater than or equal to 10% and less than or equal to 45%, greater than or equal to 10% and less than or equal to 40%, greater than or equal to 10% and less than or equal to 35%, greater than or equal to 10% and less than or equal to 30%, greater than or equal to 10% and less than or equal to 25%, greater than or equal to 10% and less than or equal to 20%, or greater than or equal to 10% and less than or equal to 15%.

[0077] A method for forming a copper oxide coated cobalt oxide according to embodiments disclosed and described herein will now be described. One method for depositing copper oxide on cobalt oxide is atomic layer deposition (ALD). ALD is a sequential deposition technique using a vapor-phase chemical process. ALD uses the reaction of two chemical precursors that react with the surface of cobalt oxide particles in a sequential, self-limiting manner. By repeatedly exposing the individual chemical precursors, a copper oxide film is slowly deposited on the cobalt oxide particles. For example, a first precursor reacts with reaction sites on the surface of the cobalt oxide particles and excess first precursor is removed from the system. Once excess first precursor is removed, a second precursor is introduced into the system. The second precursor reacts with the first precursor to form a copper oxide layer on the surface of the cobalt oxide, and excess second precursor is removed from the system. Suitable copper precursors according to embodiments include Cu(NO3)2, CuCl2, CuSO4, Cu(CH3COO)2, and combinations thereof.

[0078] Although ALD is a technically suitable method for depositing copper oxides on cobalt oxide surfaces, the ALD process is expensive, time-consuming, and difficult to scale up to a commercially viable level. Therefore, other methods for depositing copper oxides on cobalt oxides include wet chemical methods.

[0079] According to the embodiment, a first wet chemical method can be used starting with a solution of copper nitrate (Cu(NO3)2) and cobalt oxide (Co3O4) particles in the Cu(NO3)2 solution, the copper nitrate (Cu(NO3)2) solution having a concentration greater than or equal to 0.0001 M and less than or equal to 0.1 M. Sodium hydroxide (NaOH) with a concentration greater than or equal to 0.1 M and less than or equal to 1 M is introduced into the solution as a precipitant. Cu(NO3)2 and the NaOH precipitant react to form copper hydroxide (Cu(OH)2) and sodium nitrate (NaNO3) precipitates. Cu(OH)2 and NaNO3 begin to coat the Co3O4 particles, thereby forming Cu(OH)2 and NaNO3-coated Co3O4. Some Cu(OH)2 and / or NaNO3 precipitates out of the solution. According to the embodiment, the mixture is stored at room temperature overnight (e.g., from greater than or equal to 8 to less than or equal to 15 hours). The NaNO3 on the Co3O4 particles is removed by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution was filtered to obtain Cu(OH)2-coated Co3O4. The Cu(OH)2-coated Co3O4 was then dried at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0080] According to the implementation plan, the Cu(OH)2-coated Co3O4 is dried at a temperature greater than or equal to 105℃ and less than or equal to 140℃, such as greater than or equal to 110℃ and less than or equal to 140℃, greater than or equal to 115℃ and less than or equal to 140℃, greater than or equal to 120℃ and less than or equal to 140℃, greater than or equal to 125℃ and less than or equal to 140℃, greater than or equal to 130℃ and less than or equal to 140℃, greater than or equal to 135℃ and less than or equal to 140℃, greater than or equal to 100℃ and less than or equal to 135℃, greater than or equal to 105℃ and less than or equal to 135℃, and so on. The following temperatures are considered acceptable: 110℃ and less than or equal to 135℃, 115℃ and less than or equal to 135℃, 120℃ and less than or equal to 135℃, 125℃ and less than or equal to 135℃, 130℃ and less than or equal to 135℃, 100℃ and less than or equal to 135℃, 105℃ and less than or equal to 135℃, 110℃ and less than or equal to 135℃, 115℃ and less than or equal to 135℃, 120℃ and less than or equal to 135℃, 125℃ and less than or equal to 135℃, and so on. 130℃ and less than or equal to 135℃, 100℃ and less than or equal to 130℃, 105℃ and less than or equal to 130℃, 110℃ and less than or equal to 130℃, 115℃ and less than or equal to 130℃, 120℃ and less than or equal to 130℃, 125℃ and less than or equal to 130℃, 100℃ and less than or equal to 125℃, 105℃ and less than or equal to 125℃, 110℃ and less than or equal to 125℃, 115℃ and less than or equal to 125℃, and more than... Or equal to 120℃ and less than or equal to 125℃, greater than or equal to 100℃ and less than or equal to 120℃, greater than or equal to 105℃ and less than or equal to 120℃, greater than or equal to 110℃ and less than or equal to 120℃, greater than or equal to 115℃ and less than or equal to 120℃, greater than or equal to 100℃ and less than or equal to 115℃, greater than or equal to 105℃ and less than or equal to 115℃, greater than or equal to 110℃ and less than or equal to 115℃, greater than or equal to 100℃ and less than or equal to 110℃, greater than or equal to 105℃ and less than or equal to 110℃, or greater than or equal to 100℃ and less than or equal to 105℃.

[0081] According to the implementation plan, the Cu(OH)2-coated Co3O4 is dried for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, greater than or equal to 1.0 hour and less than or equal to 5.0 hours. 4.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours, greater than The following are possible time ranges: 3.0 hours and less than or equal to 4.0 hours; 3.5 hours and less than or equal to 4.0 hours; 0.5 hours and less than or equal to 3.5 hours; 1.0 hour and less than or equal to 3.5 hours; 1.5 hours and less than or equal to 3.5 hours; 2.0 hours and less than or equal to 3.5 hours; 2.5 hours and less than or equal to 3.5 hours; 3.0 hours and less than or equal to 3.5 hours; 0.5 hours and less than or equal to 3.0 hours; 1.0 hour and less than or equal to 3.0 hours; 1.5 hours and less than or equal to 3.0 hours; 2.0 hours and greater than or equal to 2.0 hours. And less than or equal to 3.0 hours, greater than or equal to 2.5 hours and less than or equal to 3.0 hours, greater than or equal to 0.5 hours and less than or equal to 2.5 hours, greater than or equal to 1.0 hour and less than or equal to 2.5 hours, greater than or equal to 1.5 hours and less than or equal to 2.5 hours, greater than or equal to 2.0 hours and less than or equal to 2.5 hours, greater than or equal to 0.5 hours and less than or equal to 2.0 hours, greater than or equal to 1.0 hour and less than or equal to 2.0 hours, greater than or equal to 1.5 hours and less than or equal to 2.0 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours, greater than or equal to 1.0 hour and less than or equal to 1.5 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours.0 hours.

[0082] According to the implementation plan, the dried Cu(OH)2 coated Co3O4 is calcined at a temperature of 430°C or higher and 470°C or lower for a duration of 0.5 hours or higher and 5.0 hours or lower.

[0083] In one or more embodiments, the dried Cu(OH)₂-coated Co₃O₄ is calcined at a calcination temperature greater than or equal to 435°C and less than or equal to 470°C, such as greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 445°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 470°C, greater than or equal to 455°C and less than or equal to 470°C, greater than or equal to 460°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 455°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 465 ... 430℃ and less than or equal to 465℃, greater than or equal to 435℃ and less than or equal to 465℃, greater than or equal to 440℃ and less than or equal to 465℃, greater than or equal to 445℃ and less than or equal to 465℃, greater than or equal to 450℃ and less than or equal to 465℃, greater than or equal to 455℃ and less than or equal to 465℃, greater than or equal to 460℃ and less than or equal to 465℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 435℃ and less than or equal to 460℃, greater than or equal to 440℃ And less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 460℃, greater than or equal to 450℃ and less than or equal to 460℃, greater than or equal to 455℃ and less than or equal to 460℃, greater than or equal to 430℃ and less than or equal to 455℃, greater than or equal to 435℃ and less than or equal to 455℃, greater than or equal to 440℃ and less than or equal to 455℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 450℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 45 ... 450℃, greater than or equal to 435℃ and less than or equal to 450℃, greater than or equal to 440℃ and less than or equal to 450℃, greater than or equal to 445℃ and less than or equal to 450℃, greater than or equal to 430℃ and less than or equal to 445℃, greater than or equal to 435℃ and less than or equal to 445℃, greater than or equal to 440℃ and less than or equal to 445℃, greater than or equal to 430℃ and less than or equal to 440℃, greater than or equal to 435℃ and less than or equal to 440℃, or greater than or equal to 430℃ and less than or equal to 435℃.

[0084] According to the implementation plan, the dried Cu(OH)2-coated Co3O4 is calcined for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, or greater than or equal to 1.0 hour. And less than or equal to 4.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours. 4.0 hours, greater than or equal to 3.0 hours and less than or equal to 4.0 hours, greater than or equal to 3.5 hours and less than or equal to 4.0 hours, greater than or equal to 0.5 hours and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to 3.5 hours, greater than or equal to 1.5 hours and less than or equal to 3.5 hours, greater than or equal to 2.0 hours and less than or equal to 3.5 hours, greater than or equal to 2.5 hours and less than or equal to 3.5 hours, greater than or equal to 3.0 hours and less than or equal to 3.5 hours, greater than or equal to 0.5 hours and less than or equal to 3.0 hours, greater than or equal to 1.0 hour and less than or equal to 3.0 hours, greater than or equal to 1.5 hours and less than or equal to 3.0 hours, Greater than or equal to 2.0 hours and less than or equal to 3.0 hours, greater than or equal to 2.5 hours and less than or equal to 3.0 hours, greater than or equal to 0.5 hours and less than or equal to 2.5 hours, greater than or equal to 1.0 hour and less than or equal to 2.5 hours, greater than or equal to 1.5 hours and less than or equal to 2.5 hours, greater than or equal to 2.0 hours and less than or equal to 2.5 hours, greater than or equal to 0.5 hours and less than or equal to 2.0 hours, greater than or equal to 1.0 hour and less than or equal to 2.0 hours, greater than or equal to 1.5 hours and less than or equal to 2.0 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours, greater than or equal to 0.5 hours.5 hours and less than or equal to 1.0 hour.

[0085] After calcination, cobalt oxide (Co3O4) particles coated with copper oxide (CuO) were obtained.

[0086] According to the embodiment, the second wet chemical method can be used starting from a copper nitrate (Cu(NO3)2) solution and cobalt oxide (Co3O4) particles in the Cu(NO3)2 solution, the copper nitrate (Cu(NO3)2) solution having a concentration greater than or equal to 0.0001 M and less than or equal to 0.1 M. Sodium carbonate (NaCO3) is introduced into the solution as a precipitant. The Cu(NO3)2 and NaCO3 precipitant react to form copper carbonate (CuCO3) and sodium nitrate (NaNO3) precipitates. CuCO3 and NaNO3 begin to coat the Co3O4 particles, thereby forming CuCO3 and NaNO3 coated Co3O4. Some CuCO3 and / or NaNO3 precipitates out of the solution. According to the embodiment, the mixture can be stored overnight (e.g., greater than or equal to 8 hours and less than or equal to 15 hours) at room temperature (e.g., from greater than or equal to 20°C and less than or equal to 25°C). The NaNO3 on the Co3O4 particles is removed by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution was filtered to obtain CuCO3-coated Co3O4. The CuCO3-coated Co3O4 was then dried at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

[0087] According to the implementation plan, the CuCO3-coated Co3O4 is dried at a temperature greater than or equal to 105°C and less than or equal to 140°C, such as greater than or equal to 110°C and less than or equal to 140°C, greater than or equal to 115°C and less than or equal to 140°C, greater than or equal to 120°C and less than or equal to 140°C, greater than or equal to 125°C and less than or equal to 140°C, greater than or equal to 130°C and less than or equal to 140°C, greater than or equal to 135°C and less than or equal to 140°C, greater than or equal to 100°C and less than or equal to 135°C, greater than or equal to 105°C and less than or equal to 135°C. ℃, greater than or equal to 110℃ and less than or equal to 135℃, greater than or equal to 115℃ and less than or equal to 135℃, greater than or equal to 120℃ and less than or equal to 135℃, greater than or equal to 125℃ and less than or equal to 135℃, greater than or equal to 130℃ and less than or equal to 135℃, greater than or equal to 100℃ and less than or equal to 135℃, greater than or equal to 105℃ and less than or equal to 135℃, greater than or equal to 110℃ and less than or equal to 135℃, greater than or equal to 115℃ and less than or equal to 135℃, greater than or equal to 120℃ and less than or equal to 135℃, greater than or equal to 125℃ and less than 135℃ or higher, 130℃ or higher and less than or equal to 135℃, 100℃ or higher and less than or equal to 130℃, 105℃ or higher and less than or equal to 130℃, 115℃ or higher and less than or equal to 130℃, 120℃ or higher and less than or equal to 130℃, 125℃ or higher and less than or equal to 130℃, 100℃ or higher and less than or equal to 125℃, 105℃ or higher and less than or equal to 125℃, 110℃ or higher and less than or equal to 125℃, 115℃ or higher and less than or equal to 125℃, 13 ... 20℃ and less than or equal to 125℃, greater than or equal to 100℃ and less than or equal to 120℃, greater than or equal to 105℃ and less than or equal to 120℃, greater than or equal to 110℃ and less than or equal to 120℃, greater than or equal to 115℃ and less than or equal to 120℃, greater than or equal to 100℃ and less than or equal to 115℃, greater than or equal to 105℃ and less than or equal to 115℃, greater than or equal to 110℃ and less than or equal to 115℃, greater than or equal to 100℃ and less than or equal to 110℃, greater than or equal to 105℃ and less than or equal to 110℃, or greater than or equal to 100℃ and less than or equal to 105℃.

[0088] According to the implementation plan, the CuCO3-coated Co3O4 is dried for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, greater than or equal to 1.0 hour and... Less than or equal to 4.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours 0 hours, greater than or equal to 3.0 hours and less than or equal to 4.0 hours, greater than or equal to 3.5 hours and less than or equal to 4.0 hours, greater than or equal to 0.5 hours and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to 3.5 hours, greater than or equal to 1.5 hours and less than or equal to 3.5 hours, greater than or equal to 2.0 hours and less than or equal to 3.5 hours, greater than or equal to 2.5 hours and less than or equal to 3.5 hours, greater than or equal to 3.0 hours and less than or equal to 3.5 hours, greater than or equal to 0.5 hours and less than or equal to 3.0 hours, greater than or equal to 1.0 hour and less than or equal to 3.0 hours, greater than or equal to 1.5 hours and less than or equal to 3.0 hours, greater ... The following are considered time ranges: 2.0 hours or less than or equal to 3.0 hours; 2.5 hours or more than or equal to 3.0 hours; 0.5 hours or more than or equal to 2.5 hours; 1.0 hour or more than or equal to 2.5 hours; 1.5 hours or more than or equal to 2.5 hours; 2.0 hours or more than or equal to 2.5 hours; 0.5 hours or more than or equal to 2.0 hours; 1.0 hour or more than or equal to 2.0 hours; 1.5 hours or more than or equal to 2.0 hours; 0.5 hours or more than or equal to 1.5 hours; 1.0 hour or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours.5 hours and less than or equal to 1.0 hour.

[0089] According to the implementation plan, the dried CuCO3-coated Co3O4 is calcined at a temperature of 430°C or higher and 470°C for a duration of 0.5 hours to 5.0 hours.

[0090] In one or more embodiments, the dried Cu(OH)₂-coated Co₃O₄ is calcined at a calcination temperature greater than or equal to 435°C and less than or equal to 470°C, such as greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 445°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 470°C, greater than or equal to 455°C and less than or equal to 470°C, greater than or equal to 460°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 455°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 465 ... 430℃ and less than or equal to 465℃, greater than or equal to 435℃ and less than or equal to 465℃, greater than or equal to 440℃ and less than or equal to 465℃, greater than or equal to 445℃ and less than or equal to 465℃, greater than or equal to 450℃ and less than or equal to 465℃, greater than or equal to 455℃ and less than or equal to 465℃, greater than or equal to 460℃ and less than or equal to 465℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 435℃ and less than or equal to 460℃, greater than or equal to 440℃ And less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 460℃, greater than or equal to 450℃ and less than or equal to 460℃, greater than or equal to 455℃ and less than or equal to 460℃, greater than or equal to 430℃ and less than or equal to 455℃, greater than or equal to 435℃ and less than or equal to 455℃, greater than or equal to 440℃ and less than or equal to 455℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 450℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 45 ... 450℃, greater than or equal to 435℃ and less than or equal to 450℃, greater than or equal to 440℃ and less than or equal to 450℃, greater than or equal to 445℃ and less than or equal to 450℃, greater than or equal to 430℃ and less than or equal to 445℃, greater than or equal to 435℃ and less than or equal to 445℃, greater than or equal to 440℃ and less than or equal to 445℃, greater than or equal to 430℃ and less than or equal to 440℃, greater than or equal to 435℃ and less than or equal to 440℃, or greater than or equal to 430℃ and less than or equal to 435℃.

[0091] According to the implementation plan, the dried CuCO3-coated Co3O4 is calcined for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, greater than or equal to 1.0 hour and... Less than or equal to 4.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours 0 hours, greater than or equal to 3.0 hours and less than or equal to 4.0 hours, greater than or equal to 3.5 hours and less than or equal to 4.0 hours, greater than or equal to 0.5 hours and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to 3.5 hours, greater than or equal to 1.5 hours and less than or equal to 3.5 hours, greater than or equal to 2.0 hours and less than or equal to 3.5 hours, greater than or equal to 2.5 hours and less than or equal to 3.5 hours, greater than or equal to 3.0 hours and less than or equal to 3.5 hours, greater than or equal to 0.5 hours and less than or equal to 3.0 hours, greater than or equal to 1.0 hour and less than or equal to 3.0 hours, greater than or equal to 1.5 hours and less than or equal to 3.0 hours, greater ... The following are considered time ranges: 2.0 hours or less than or equal to 3.0 hours; 2.5 hours or more than or equal to 3.0 hours; 0.5 hours or more than or equal to 2.5 hours; 1.0 hour or more than or equal to 2.5 hours; 1.5 hours or more than or equal to 2.5 hours; 2.0 hours or more than or equal to 2.5 hours; 0.5 hours or more than or equal to 2.0 hours; 1.0 hour or more than or equal to 2.0 hours; 1.5 hours or more than or equal to 2.0 hours; 0.5 hours or more than or equal to 1.5 hours; 1.0 hour or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours.5 hours and less than or equal to 1.0 hour.

[0092] After calcination, cobalt oxide (Co3O4) particles coated with copper oxide (CuO) are obtained. According to one embodiment, the Co3O4 particles initially present in the Cu(NO3)2 solution can be replaced with a cobalt nitrate (Co(NO3)2) solution. According to one or more embodiments, the ratio of cobalt to copper is greater than or equal to 1:1 and less than or equal to 9:1, such as greater than or equal to 1:1 and less than or equal to 8:1, greater than or equal to 1:1 and less than or equal to 7:1, greater than or equal to 1:1 and less than or equal to 6:1, greater than or equal to 1:1 and less than or equal to 5:1, greater than or equal to 1:1 and less than or equal to 4:1, greater than or equal to 1:1 and less than or equal to 3:1, or greater than or equal to 1:1 and less than or equal to 2:1. According to one embodiment, the precipitant includes NaOH, Na2CO3, (NH4)2CO3, and mixtures thereof.

[0093] According to the implementation scheme, the third wet chemical method can be used starting from a solution of copper nitrate (Cu(NO3)2) and cobalt oxide (Co3O4) particles in the Cu(NO3)2 solution, wherein the copper nitrate (Cu(NO3)2) solution has a concentration greater than or equal to 0.0001 M and less than or equal to 0.1 M. Ammonium carbonate ((NH4)2CO3) is introduced into the solution as a precipitant. In this wet chemical method, an ammonium-based precipitant is used instead of the sodium-based precipitant used in the first and second wet chemical methods. The sodium-based precipitate formed by the sodium-based precipitant can interfere with the reaction and reduce the yield of CuO-coated Co3O4. The Cu(NO3)2 and (NH4)2CO3 precipitant react to form copper carbonate (CuCO3) and ammonium nitrate ((NH4)2NO3) precipitates. CuCO3 and (NH4)2NO3 begin to coat the Co3O4 particles, thereby forming CuCO3 and (NH4)2NO3-coated Co3O4. Some CuCO3 and / or (NH4)2NO3 precipitate from the solution. According to the embodiment, the mixture can be stored overnight (e.g., 8 hours to 15 hours) at room temperature (e.g., from 20°C to 25°C). (NH4)2NO3 is removed from the Co3O4 particles by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution is filtered to obtain CuCO3-coated Co3O4. The CuCO3-coated Co3O4 is then dried at a temperature of 100°C to 140°C for a duration of 0.5 hours to 5.0 hours.

[0094] According to the implementation plan, the CuCO3-coated Co3O4 is dried at a temperature greater than or equal to 105℃ and less than or equal to 140℃, such as greater than or equal to 110℃ and less than or equal to 140℃, greater than or equal to 115℃ and less than or equal to 140℃, greater than or equal to 120℃ and less than or equal to 140℃, greater than or equal to 125℃ and less than or equal to 140℃, greater than or equal to 130℃ and less than or equal to 140℃, greater than or equal to 135℃ and less than or equal to 140℃, greater than or equal to 100℃ and less than or equal to 135℃, greater than or equal to 105℃ and less than or equal to 135℃, greater than or equal to 1... 10℃ and less than or equal to 135℃, greater than or equal to 115℃ and less than or equal to 135℃, greater than or equal to 120℃ and less than or equal to 135℃, greater than or equal to 125℃ and less than or equal to 135℃, greater than or equal to 130℃ and less than or equal to 135℃, greater than or equal to 100℃ and less than or equal to 135℃, greater than or equal to 105℃ and less than or equal to 135℃, greater than or equal to 110℃ and less than or equal to 135℃, greater than or equal to 115℃ and less than or equal to 135℃, greater than or equal to 120℃ and less than or equal to 135℃, greater than or equal to 125℃ and less than or equal to 135℃, greater ...35℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, greater than or equal to 135℃, The following temperatures are considered acceptable: 130℃ and less than or equal to 135℃, 100℃ and less than or equal to 130℃, 105℃ and less than or equal to 130℃, 110℃ and less than or equal to 130℃, 115℃ and less than or equal to 130℃, 120℃ and less than or equal to 130℃, 125℃ and less than or equal to 130℃, 100℃ and less than or equal to 125℃, 105℃ and less than or equal to 125℃, 110℃ and less than or equal to 125℃, and 115℃ and less than or equal to 125℃. Or equal to 120℃ and less than or equal to 125℃, greater than or equal to 100℃ and less than or equal to 120℃, greater than or equal to 105℃ and less than or equal to 120℃, greater than or equal to 110℃ and less than or equal to 120℃, greater than or equal to 115℃ and less than or equal to 120℃, greater than or equal to 100℃ and less than or equal to 115℃, greater than or equal to 105℃ and less than or equal to 115℃, greater than or equal to 110℃ and less than or equal to 115℃, greater than or equal to 100℃ and less than or equal to 110℃, greater than or equal to 105℃ and less than or equal to 110℃, or greater than or equal to 100℃ and less than or equal to 105℃.

[0095] According to the implementation plan, the CuCO3-coated CO3O4 is dried for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours. 0.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours, greater ... =3.0 hours and less than or equal to 4.0 hours, greater than or equal to 3.5 hours and less than or equal to 4.0 hours, greater than or equal to 0.5 hours and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to 3.5 hours, greater than or equal to 1.5 hours and less than or equal to 3.5 hours, greater than or equal to 2.0 hours and less than or equal to 3.5 hours, greater than or equal to 2.5 hours and less than or equal to 3.5 hours, greater than or equal to 3.0 hours and less than or equal to 3.5 hours, greater than or equal to 0.5 hours and less than or equal to 3.0 hours, greater than or equal to 1.0 hour and less than or equal to 3.0 hours, greater than or equal to 1.5 hours and less than or equal to 3.0 hours, greater than or equal to 2.0 hours And less than or equal to 3.0 hours, greater than or equal to 2.5 hours and less than or equal to 3.0 hours, greater than or equal to 0.5 hours and less than or equal to 2.5 hours, greater than or equal to 1.0 hour and less than or equal to 2.5 hours, greater than or equal to 1.5 hours and less than or equal to 2.5 hours, greater than or equal to 2.0 hours and less than or equal to 2.5 hours, greater than or equal to 0.5 hours and less than or equal to 2.0 hours, greater than or equal to 1.0 hour and less than or equal to 2.0 hours, greater than or equal to 1.5 hours and less than or equal to 2.0 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours, greater than or equal to 1.0 hour and less than or equal to 1.5 hours, greater than or equal to 0.5 hours and less than or equal to 1.5 hours.0 hours.

[0096] According to the implementation plan, the dried CuCO3-coated Co3O4 is calcined at a temperature of 430°C or higher and 470°C for a duration of 0.5 hours to 5.0 hours.

[0097] In one or more embodiments, the dried Cu(OH)₂-coated Co₃O₄ is calcined at a calcination temperature greater than or equal to 435°C and less than or equal to 470°C, such as greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 445°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 470°C, greater than or equal to 455°C and less than or equal to 470°C, greater than or equal to 460°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 465°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 450°C and less than or equal to 455°C and less than or equal to 470°C, greater than or equal to 435°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 470°C, greater than or equal to 465 ... 430℃ and less than or equal to 465℃, greater than or equal to 435℃ and less than or equal to 465℃, greater than or equal to 440℃ and less than or equal to 465℃, greater than or equal to 445℃ and less than or equal to 465℃, greater than or equal to 450℃ and less than or equal to 465℃, greater than or equal to 455℃ and less than or equal to 465℃, greater than or equal to 460℃ and less than or equal to 465℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 435℃ and less than or equal to 460℃, greater than or equal to 440℃ And less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 460℃, greater than or equal to 450℃ and less than or equal to 460℃, greater than or equal to 455℃ and less than or equal to 460℃, greater than or equal to 430℃ and less than or equal to 455℃, greater than or equal to 435℃ and less than or equal to 455℃, greater than or equal to 440℃ and less than or equal to 455℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 450℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 430℃ and less than or equal to 460℃, greater than or equal to 445℃ and less than or equal to 455℃, greater than or equal to 45 ... 450℃, greater than or equal to 435℃ and less than or equal to 450℃, greater than or equal to 440℃ and less than or equal to 450℃, greater than or equal to 445℃ and less than or equal to 450℃, greater than or equal to 430℃ and less than or equal to 445℃, greater than or equal to 435℃ and less than or equal to 445℃, greater than or equal to 440℃ and less than or equal to 445℃, greater than or equal to 430℃ and less than or equal to 440℃, greater than or equal to 435℃ and less than or equal to 440℃, or greater than or equal to 430℃ and less than or equal to 435℃.

[0098] According to the implementation plan, the dried CuCO3-coated Co3O4 is calcined for a duration greater than or equal to 1.0 hour and less than or equal to 5.0 hours, such as greater than or equal to 1.5 hours and less than or equal to 5.0 hours, greater than or equal to 2.0 hours and less than or equal to 5.0 hours, greater than or equal to 2.5 hours and less than or equal to 5.0 hours, greater than or equal to 3.0 hours and less than or equal to 5.0 hours, greater than or equal to 3.5 hours and less than or equal to 5.0 hours, greater than or equal to 4.0 hours and less than or equal to 5.0 hours, greater than or equal to 4.5 hours and less than or equal to 5.0 hours, greater than or equal to 0.5 hours and less than or equal to 4.5 hours, greater than or equal to 1.0 hour and... Less than or equal to 4.5 hours, greater than or equal to 1.5 hours and less than or equal to 4.5 hours, greater than or equal to 2.0 hours and less than or equal to 4.5 hours, greater than or equal to 2.5 hours and less than or equal to 4.5 hours, greater than or equal to 3.0 hours and less than or equal to 4.5 hours, greater than or equal to 3.5 hours and less than or equal to 4.5 hours, greater than or equal to 4.0 hours and less than or equal to 4.5 hours, greater than or equal to 0.5 hours and less than or equal to 4.0 hours, greater than or equal to 1.0 hour and less than or equal to 4.0 hours, greater than or equal to 1.5 hours and less than or equal to 4.0 hours, greater than or equal to 2.0 hours and less than or equal to 4.0 hours, greater than or equal to 2.5 hours and less than or equal to 4.0 hours 0 hours, greater than or equal to 3.0 hours and less than or equal to 4.0 hours, greater than or equal to 3.5 hours and less than or equal to 4.0 hours, greater than or equal to 0.5 hours and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to 3.5 hours, greater than or equal to 1.5 hours and less than or equal to 3.5 hours, greater than or equal to 2.0 hours and less than or equal to 3.5 hours, greater than or equal to 2.5 hours and less than or equal to 3.5 hours, greater than or equal to 3.0 hours and less than or equal to 3.5 hours, greater than or equal to 0.5 hours and less than or equal to 3.0 hours, greater than or equal to 1.0 hour and less than or equal to 3.0 hours, greater than or equal to 1.5 hours and less than or equal to 3.0 hours, greater ... The following are considered time ranges: 2.0 hours or less than or equal to 3.0 hours; 2.5 hours or more than or equal to 3.0 hours; 0.5 hours or more than or equal to 2.5 hours; 1.0 hour or more than or equal to 2.5 hours; 1.5 hours or more than or equal to 2.5 hours; 2.0 hours or more than or equal to 2.5 hours; 0.5 hours or more than or equal to 2.0 hours; 1.0 hour or more than or equal to 2.0 hours; 1.5 hours or more than or equal to 2.0 hours; 0.5 hours or more than or equal to 1.5 hours; 1.0 hour or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours; 0.5 hours or more than or equal to 1.5 hours.5 hours and less than or equal to 1.0 hour.

[0099] After calcination, cobalt oxide (Co3O4) particles coated with copper oxide (CuO) were obtained.

[0100] The method for forming copper oxide (CuO) coated carbon black particles will now be described.

[0101] A thin layer of CuO is applied to the surface of carbon black by ALD, similar to the method of depositing CuO on Co3O4 described above, but CuO is deposited onto carbon black particles by using the precursors disclosed above.

[0102] As mentioned above, although ALD is a technically suitable method for depositing copper oxides on carbon black surfaces, the ALD process is expensive, time-consuming, and difficult to scale up to a commercially viable level. Therefore, other methods for depositing copper oxides on carbon black include wet chemical methods.

[0103] According to the implementation scheme, the wet chemical method can be used starting with a solution of copper nitrate (Cu(NO3)2) and carbon black particles in the Cu(NO3)2 solution, wherein the copper nitrate (Cu(NO3)2) solution has a concentration greater than or equal to 0.0001 M and less than or equal to 0.1 M. NaCO3, (NH4)2CO3, or NaOH is introduced into the solution as a precipitant. A certain proportion of Cu(NO3)2 and the precipitant react to form Cu(OH)2 or CuCO3 (depending on the precipitant) and NaNO3 or (NH4)2NO3 precipitates (depending on the precipitant). The carbon black particles are coated with (Cu(OH)2) and / or CuCO3. The NaNO3 and / or (NH4)2NO3 are then removed by washing the precipitate with water and ethanol. The solution can then be filtered to obtain Cu(OH)2-coated carbon black or CuCO3-coated carbon black. The precipitate was then dried at a temperature of 100°C or higher and 140°C for a duration of 5 hours or higher and 15 hours or lower.

[0104] According to the implementation plan, the carbon black coated with CuCO3 and / or Cu(OH)2 is dried at a temperature greater than or equal to 105°C and less than or equal to 140°C, such as greater than or equal to 110°C and less than or equal to 140°C, greater than or equal to 115°C and less than or equal to 140°C, greater than or equal to 120°C and less than or equal to 140°C, greater than or equal to 125°C and less than or equal to 140°C, greater than or equal to 130°C and less than or equal to 140°C, greater than or equal to 135°C and less than or equal to 140°C, greater than or equal to 100°C and less than or equal to 135°C, greater than or equal to 105°C and less than or equal to 135°C, etc. The following temperatures are considered high: 110℃ and less than or equal to 135℃; 115℃ and less than or equal to 135℃; 120℃ and less than or equal to 135℃; 125℃ and less than or equal to 135℃; 130℃ and less than or equal to 135℃; 100℃ and less than or equal to 135℃; 105℃ and less than or equal to 135℃; 110℃ and less than or equal to 135℃; 115℃ and less than or equal to 135℃; 120℃ and less than or equal to 135℃; 125℃ and less than or equal to 135℃; and so on. The following temperatures are considered high: 130℃ and less than or equal to 135℃; 100℃ and less than or equal to 130℃; 105℃ and less than or equal to 130℃; 110℃ and less than or equal to 130℃; 115℃ and less than or equal to 130℃; 120℃ and less than or equal to 130℃; 125℃ and less than or equal to 130℃; 100℃ and less than or equal to 125℃; 105℃ and less than or equal to 125℃; 110℃ and less than or equal to 125℃; 115℃ and less than or equal to 125℃; and so on. The following temperatures are considered acceptable: 120℃ and less than or equal to 125℃, 100℃ and less than or equal to 120℃, 105℃ and less than or equal to 120℃, 110℃ and less than or equal to 120℃, 115℃ and less than or equal to 120℃, 100℃ and less than or equal to 115℃, 105℃ and less than or equal to 115℃, 110℃ and less than or equal to 115℃, 100℃ and less than or equal to 110℃, 105℃ and less than or equal to 110℃, or 100℃ and less than or equal to 105℃.

[0105] According to the implementation plan, the carbon black coated with CuCO3 and / or Cu(OH)2 is dried for a duration of 6 hours or more and 15 hours or 7 hours or more and 15 hours or more.Such as 8 hours or more and 15 hours or less, 9 hours or more and 15 hours or less, 10 hours or more and 15 hours or less, 11 hours or more and 15 hours or less, 12 hours or more and 15 hours or less, 13 hours or more and 15 hours or less, 14 hours or more and 15 hours or less, 5 hours or more and 14 hours or less, 6 hours or more and 14 hours or less, 7 hours or more and 14 hours or less, 8 hours or more and 14 hours or more, 9 hours or more and 14 hours or less, 10 hours or more and 15 hours or less, etc. Within 14 hours, greater than or equal to 11 hours and less than or equal to 14 hours, greater than or equal to 12 hours and less than or equal to 14 hours, greater than or equal to 13 hours and less than or equal to 14 hours, greater than or equal to 5 hours and less than or equal to 13 hours, greater than or equal to 6 hours and less than or equal to 13 hours, greater than or equal to 7 hours and less than or equal to 13 hours, greater than or equal to 8 hours and less than or equal to 13 hours, greater than or equal to 9 hours and less than or equal to 13 hours, greater than or equal to 10 hours and less than or equal to 13 hours, greater than or equal to 11 hours and less than or equal to 13 hours, greater than or equal to 12 hours and less than or equal to 13 hours, greater than or equal to 5 hours and less than or equal to 12 hours, greater than or equal to 6 hours and Less than or equal to 12 hours, greater than or equal to 7 hours and less than or equal to 12 hours, greater than or equal to 8 hours and less than or equal to 12 hours, greater than or equal to 9 hours and less than or equal to 12 hours, greater than or equal to 10 hours and less than or equal to 12 hours, greater than or equal to 11 hours and less than or equal to 12 hours, greater than or equal to 5 hours and less than or equal to 11 hours, greater than or equal to 6 hours and less than or equal to 11 hours, greater than or equal to 7 hours and less than or equal to 11 hours, greater than or equal to 8 hours and less than or equal to 11 hours, greater than or equal to 9 hours and less than or equal to 11 hours, greater than or equal to 10 hours and less than or equal to 11 hours, greater than or equal to 5 hours and less than or equal to 10 hours, greater than or equal to 6 hours And less than or equal to 10 hours, greater than or equal to 7 hours and less than or equal to 10 hours, greater than or equal to 8 hours and less than or equal to 10 hours, greater than or equal to 9 hours and less than or equal to 10 hours, greater than or equal to 5 hours and less than or equal to 9 hours, greater than or equal to 6 hours and less than or equal to 9 hours, greater than or equal to 7 hours and less than or equal to 9 hours, greater than or equal to 8 hours and less than or equal to 9 hours, greater than or equal to 5 hours and less than or equal to 8 hours, greater than or equal to 6 hours and less than or equal to 8 hours, greater than or equal to 7 hours and less than or equal to 8 hours, greater than or equal to 5 hours and less than or equal to 7 hours, greater than or equal to 6 hours and less than or equal to 7 hours, or greater than or equal to 5 hours and less than or equal to 6 hours.

[0106] According to the implementation scheme, the dried CuCO3 and / or Cu(OH)2 coated carbon black is calcined at a temperature greater than or equal to 200°C and less than or equal to 300°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours. From this calcination, CuO coated carbon black is obtained.

[0107] In one or more embodiments, the dried CuCO3 and / or Cu(OH)2-coated carbon black is calcined at a temperature greater than or equal to 210°C and less than or equal to 300°C, such as greater than or equal to 220°C and less than or equal to 300°C, greater than or equal to 230°C and less than or equal to 300°C, greater than or equal to 240°C and less than or equal to 300°C, greater than or equal to 250°C and less than or equal to 300°C, greater than or equal to 260°C and less than or equal to 300°C, greater than or equal to 270°C and less than or equal to 300°C, greater than or equal to 280°C and less than or equal to 300°C, greater than or equal to 290°C and less than or equal to 300°C, or greater than or equal to 200°C and less than or equal to 290°C. ≥210℃ and ≤290℃, ≥220℃ and ≤290℃, ≥230℃ and ≤290℃, ≥240℃ and ≤290℃, ≥250℃ and ≤290℃, ≥260℃ and ≤290℃, ≥270℃ and ≤290℃, ≥280℃ and ≤290℃, ≥200℃ and ≤280℃, ≥210℃ and ≤280℃, ≥220℃ and ≤280℃, ≥230℃ and ≤280℃, ≥2 40℃ and less than or equal to 280℃, greater than or equal to 250℃ and less than or equal to 280℃, greater than or equal to 260℃ and less than or equal to 280℃, greater than or equal to 270℃ and less than or equal to 280℃, greater than or equal to 200℃ and less than or equal to 270℃, greater than or equal to 210℃ and less than or equal to 270℃, greater than or equal to 220℃ and less than or equal to 270℃, greater than or equal to 230℃ and less than or equal to 270℃, greater than or equal to 240℃ and less than or equal to 270℃, greater than or equal to 250℃ and less than or equal to 270℃, greater than or equal to 260℃ and less than or equal to 270℃, greater than or equal to 200℃ and less than or equal to 260℃, greater than or equal to 210℃ and less than or equal to 280℃ 260℃ or higher, 220℃ or higher and less than or equal to 260℃, 230℃ or higher and less than or equal to 260℃, 240℃ or higher and less than or equal to 260℃, 250℃ or higher and less than or equal to 260℃, 200℃ or higher and less than or equal to 250℃, 210℃ or higher and less than or equal to 250℃, 220℃ or higher and less than or equal to 250℃, 230℃ or higher and less than or equal to 250℃, 240℃ or higher and less than or equal to 250℃, 200℃ or higher and less than or equal to 240℃, 210℃ or higher and less than or equal to 240℃, 220℃ or higher and less than or equal to 240℃The following temperatures are considered acceptable: ≥230℃ and ≤240℃; ≥200℃ and ≤230℃; ≥210℃ and ≤230℃; ≥220℃ and ≤230℃; ≥200℃ and ≤220℃; ≥210℃ and ≤220℃; or ≥200℃ and ≤210℃.

[0108] Using the method disclosed above, carbon black coated with dispersed CuO nanoparticles can be formed. Although any or a combination of NaCO3, NaOH, or (NH4)2CO3 can be used in this process, (NH4)2CO3 generally provides a better yield.

[0109] Refer again Figure 3The embodiments of the copper oxide-coated particulate system 300 will be further described—wherein the particles may be copper oxide-coated cobalt oxide or copper oxide-coated carbon black. According to an embodiment, the copper oxide-coated particulate system 300 may be a coating layer having a plurality of copper oxide-coated particles 310 in a carrier 330. According to the embodiments disclosed and described herein, the carrier 330 may be an adhesive or any type of solvent used in the coating system, such as organic solvents or water. Non-limiting examples of adhesives include enamel coating adhesives, urethane coating adhesives, combined enamel-urethane coating adhesives, acrylic adhesives, latex adhesives, etc. In an embodiment, the copper oxide-coated particulate system 300 is able to appear as a dark color to an observer viewing the copper oxide-coated particulate system 300 and reflects electromagnetic radiation in the near-infrared and lidar spectra, such as electromagnetic radiation with wavelengths from greater than about 750 nm to 1550 nm. That is, when exposed to sunlight and observed by an observer, the copper oxide-coated particulate system 300 reflecting near-infrared and lidar light has a luminance of less than or equal to 20 in the CIELAB color space and reflects electromagnetic radiation with an average value greater than 20% in the near-infrared and lidar spectrum, such as electromagnetic radiation with wavelengths from greater than about 750 nm to 1550 nm. In an embodiment, when exposed to sunlight, the copper oxide-coated particulate system 300 reflecting near-infrared and lidar light reflects electromagnetic radiation with an average value of less than 10% in the visible spectrum and has a luminance of less than or equal to 15 in the CIELAB color space. In such an embodiment, the copper oxide-coated particulate system 300 reflecting near-infrared and lidar light may have a luminance of less than or equal to 10 in the CIELAB color space when exposed to sunlight. As used herein, the term "average value" refers to the average of ten (10) reflectance values ​​at equal intervals along a specified reflectance spectrum for the deep-colored pigment reflecting near-infrared and lidar light or the copper oxide-coated particulate system 300 reflecting near-infrared and lidar light described herein. Furthermore, unless otherwise stated, the terms “more than” and “less than” used herein refer to “average reflection greater than” and “average reflection less than”, respectively.

[0110] However, in one or more embodiments, the copper oxide-coated particles 310 can be one of many different types of pigments and / or colorants in the carrier 330 of the copper oxide-coated particle system 300. For example, the copper oxide-coated particles 310 disclosed and described herein can be used in combination with other types of pigments and / or colorants added to the carrier to darken the copper oxide-coated particle system. As a non-limiting example, the copper oxide-coated particles 310 can be added to the carrier 330 together with a conventional green pigment to produce a dark green copper oxide-coated particle system 300. The copper oxide-coated particles 310 in the dark green copper oxide-coated particle system 300 will reflect a sufficient amount of near-infrared or lidar electromagnetic radiation so that the dark green copper oxide-coated particle system 300 can be detected by a near-infrared or lidar sensor. The copper oxide-coated particles according to the embodiments disclosed and described herein can be used in any coating system to darken the visual appearance of the coating system. Therefore, the copper oxide coated particles disclosed and described herein can be used without limitation anywhere black pigments—such as carbon black, cobalt oxides, and copper oxides—are used in coatings or coloring systems.

[0111] Now for reference Figure 6 and Figure 7 An embodiment of a vehicle 'V' with a dark-colored coating that reflects near-infrared and lidar signals is described herein, the coating having copper oxide coated particles disclosed and described herein. Specifically, Figure 6 A vehicle V with side panels 'S' is depicted, the side panels 'S' being coated with a dark-colored paint 50 that reflects near-infrared and lidar signals and contains copper oxide coated particles disclosed and described herein. Figure 7A cross-section of one of the side panels S of a dark-tinted coating 50 that reflects near-infrared and lidar signals is depicted. The dark-tinted coating 50 that reflects near-infrared and lidar signals may include multiple layers providing surface protection and desired color. For example, the dark-tinted coating 50 may include a phosphate layer 122, an electroplating layer 124, a primer layer 126, a color layer 112 or 114 (also referred to as a base coat or undercoat), and a clear coat 128. Non-limiting examples of phosphate layers include manganese phosphate layers, iron phosphate layers, zinc phosphate layers, and combinations thereof. Non-limiting examples of electroplating layers include anodic electroplating and cathodic electroplating. Non-limiting examples of primer layers include epoxy primer layers and polyurethane primer layers. Non-limiting examples of clear coats include polyurethane clear coats and acrylic clear coats. It should be understood that the dark-colored coating 50 reflecting near-infrared and lidar appears dark to an observer viewing the dark coating, and reflects electromagnetic radiation in the near-infrared and lidar spectrum, such as electromagnetic radiation with wavelengths from about 750 nm to 1550 nm. That is, the dark-colored coating 50 reflecting near-infrared and lidar, when exposed to sunlight and observed by an observer, has a luminance of less than or equal to 20 in the CIELAB color space, and reflects more than 40% of the electromagnetic radiation in the near-infrared and lidar spectrum, such as electromagnetic radiation with wavelengths from about 750 nm to 1550 nm. In some embodiments, the dark-colored coating 50 reflecting near-infrared and lidar exposed to sunlight reflects less than 10% of the electromagnetic radiation in the visible spectrum on average, and has a luminance of less than or equal to 15 in the CIELAB color space. In such embodiments, the dark-colored coating 50 reflecting lidar exposed to sunlight may have a luminance of less than or equal to 10 in the CIELAB color space.

[0112] The blackness of a coating system with a transparent coating can be lower than that of the pigment itself. Without being bound by any particular theory, it is believed that less light scattering from the smooth surface of the transparent coating or the lower contrast of the refractive index caused by the transparent coating results in a lower blackness value. According to embodiments, the blackness of a dark-colored coating with copper oxide-coated particles that reflects near-infrared and lidar signals has a blackness greater than or equal to 100 and less than or equal to 140, such as greater than or equal to 105 and less than or equal to 140, greater than or equal to 110 and less than or equal to 140, greater than or equal to 115 and less than or equal to 140, greater than or equal to 120 and less than or equal to 140, greater than or equal to 125 and less than or equal to 140, greater than or equal to 130 and less than or equal to 140, and greater than or equal to 135. And less than or equal to 140, greater than or equal to 100 and less than or equal to 135, such as greater than or equal to 105 and less than or equal to 135, greater than or equal to 110 and less than or equal to 135, greater than or equal to 115 and less than or equal to 135, greater than or equal to 120 and less than or equal to 135, greater than or equal to 125 and less than or equal to 135, greater than or equal to 130 and less than or equal to 135, greater than or equal to 100 and less than or equal to 130, such as greater than or equal to 105 and less than or equal to 130. Greater than or equal to 110 and less than or equal to 130, greater than or equal to 115 and less than or equal to 130, greater than or equal to 120 and less than or equal to 130, greater than or equal to 125 and less than or equal to 130, greater than or equal to 100 and less than or equal to 125, such as greater than or equal to 105 and less than or equal to 125, greater than or equal to 110 and less than or equal to 125, greater than or equal to 115 and less than or equal to 125, greater than or equal to 120 and less than or equal to 125, greater than or equal to 100 and less than Or equal to 120, such as greater than or equal to 105 and less than or equal to 120, greater than or equal to 110 and less than or equal to 120, greater than or equal to 115 and less than or equal to 120, greater than or equal to 100 and less than or equal to 115, such as greater than or equal to 105 and less than or equal to 115, greater than or equal to 110 and less than or equal to 115, greater than or equal to 100 and less than or equal to 110, such as greater than or equal to 105 and less than or equal to 110, or greater than or equal to 100 and less than or equal to 105.

[0113] As described above, copper oxide-coated particles reflecting near-infrared and lidar radiation according to embodiments disclosed and described herein can be used in coatings to provide dark-colored articles reflecting near-infrared and lidar radiation, which can be detected by systems that detect near-infrared or lidar electromagnetic radiation. There are no limitations on articles that can be coated with coatings reflecting near-infrared and lidar radiation according to embodiments disclosed and described herein. Articles such as automobiles, motorcycles, bicycles, buildings, doorways, road markings, signs, factories, docks, and warehouses can be coated with the dark-colored coatings reflecting near-infrared and lidar radiation described herein, thereby providing dark-colored articles with a desired deep color, which can also be detected by systems that detect electromagnetic radiation in the near-infrared and lidar spectra (such as electromagnetic radiation with wavelengths from greater than about 750 nm to 1550 nm).

[0114] Example

[0115] The implementation scheme will be further illustrated by the following examples.

[0116] Example 1 - Synthesis of Cobalt Oxide Pigments Coated with Copper Oxide

[0117] The following examples illustrate the synthesis of CuO / Co3O4 (i.e., 50% CuO and 50% Co3O4) in a 1:1 ratio using Na2CO3 as a precipitant. In a typical synthesis, 14.6 g of Cu(NO3)2 is dissolved in 300 mL of water. Then, 5 g of Co3O4 is dispersed in the Cu(NO3)2 solution. In another container, 10 g of Na2CO3 is dissolved in 300 mL of water. The Na2CO3 solution is then slowly added to the Cu(NO3)2 / Co3O4 solution until Cu(NO3)2 is precipitated to CuCO3. The precipitate is then aged overnight and filtered. Subsequently, the precipitate is washed with 1000 mL of water and dried at 120 °C for 12 hours at a heating rate of 2 °C / min. Finally, the material is calcined at 500 °C for 1 hour at a heating rate of 5 °C / min.

[0118] The above process was repeated with copper oxide concentrations of 23 wt% and 33 wt%. Figure 5 Photographs of cobalt oxide particles coated with copper oxide at varying percentages on cobalt oxide, taken with an infrared camera equipped with a SOLOMARK digital night vision binoculars. Figure 5 It is shown that as the weight percentage of copper oxide in the copper oxide-coated cobalt oxide increases, the reflectance of electromagnetic radiation in the near-infrared and lidar spectra increases. Figure 5 The maximum reflectance shown is for 100% copper oxide ( Figure 5 (Two groups numbered 510). However, Figure 5The significant reflectance of the copper oxide-coated cobalt oxide particles, as described above, is shown. Specifically, Figure 5 The reflectance of copper oxide coated cobalt oxide particles for electromagnetic radiation in near-infrared and lidar spectra is shown. The particles contain 23 wt% copper oxide (520), 33 wt% copper oxide (530), and 50 wt% copper oxide (540).

[0119] The blackness of the cobalt oxide coated with copper oxide containing 50 wt% copper oxide is shown in Figure 4 (CuO-Co3O4 stripes), measured using an X-Rite Ci7600. The measured blackness is approximately 160 M. C .

[0120] Example 2 - Cobalt oxide coating system with copper oxide coating

[0121] A 3-inch x 5-inch aluminum panel coated with black and white paint was obtained, and the paint system was applied to the panel using an 8-path wet film applicator from Paul N. Gardner Company, Inc. (Pompano Beach, FL).

[0122] 2 g of Basecoat Balancer ChromaBase 150K and 0.5 g of the pigment prepared above were mixed in a vortex for 1 minute, followed by ultrasonic treatment for 30 minutes. The mixture was then transferred to an A-250 mixer and mixed for another 10 seconds to form a homogeneous paste. A coating was prepared on an aluminum panel using a drawdown method with an applicator with a gap of 8 mil (0.20 mm), and then cured overnight at room temperature. The blackness of the panel was then measured as described above (before applying the clear coat). The blackness exceeded 156 M. y And shown to Figure 8 middle.

[0123] Comparative samples were prepared by replacing the pigments according to the embodiments disclosed and described herein with carbon black, cold black, commercial copper oxide, ball-milled copper oxide (commercial copper oxide that has been ball-milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide. The blackness of these comparative samples is also shown in… Figure 8 As can be seen, the blackness of the cobalt oxide coated with copper oxide according to the embodiments disclosed and described herein is similar to that of carbon black and is much higher than that of cold black, commercial copper oxide, ball-milled copper oxide (commercial copper oxide that has been ball-milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide.

[0124] To apply the clear coat, PPG Deltron DC4000 and Deltron DC3085 were mixed in a 4:1 ratio under vortex for 1 minute, followed by ultrasonic treatment for 5 minutes. The mixture was then transferred to an A-250 mixer and mixed for another 30 seconds to form a homogeneous clear liquid. A pull-type clear coat was applied to the above-mentioned massstone coating using an applicator with an 8 mil (0.20 mm) gap, followed by curing at room temperature for 10 minutes and then at 60°C for 20 minutes. The blackness of the panel (after applying the clear coat) was then measured as described above. The blackness exceeded 132 M. y And shown to Figure 9 In addition, a transparent coating was applied to the comparison samples, and the blackness of these comparison samples with the transparent coating was measured. The blackness of these comparison samples is also shown in... Figure 9 As can be seen, the blackness of the cobalt oxide coated with copper oxide according to the disclosed and described embodiments is similar to that of carbon black, and is much higher than that of cold black, commercial copper oxide, ball-milled copper oxide (commercial copper oxide that has been ball-milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide.

[0125] The reflectance of a panel with a transparent coating, using pigments of cobalt oxide coated with copper oxide, was measured as disclosed herein and is shown in... Figure 10 In addition, the reflectance of the samples was measured and compared, and in Figure 10 The report states that, as shown, the reflectance of copper oxide-coated cobalt oxide is almost the same as that of carbon black in the visible spectrum, but exhibits significantly higher reflectance in the near-infrared and lidar electromagnetic radiation wavelength ranges. It is also believed that increasing the pigment loading of copper oxide-coated cobalt oxide within the coating system can increase the reflectance of transparently coated panels using copper oxide-coated cobalt oxide pigments in the near-infrared and lidar electromagnetic radiation wavelength ranges.

[0126] The intensity of a lidar sensor with a transparent coating, using a cobalt oxide pigment coated with copper oxide, is measured as disclosed herein, and is shown in... Figure 11 In addition, the lidar intensity of the samples was measured and compared. Figure 11 The report states that, as shown, the lidar intensity of copper oxide-coated cobalt oxide is significantly higher than that of carbon black.

[0127] The aforementioned samples and comparative samples demonstrate that pigments formed from cobalt oxide coated with copper oxide possess blackness and reflectivity in the visible spectrum, similar to current standard carbon black used in many black pigment applications (e.g., automotive coating systems). However, cobalt oxide pigments coated with copper oxide also offer reflectivity exceeding that of carbon black in the near-infrared and lidar electromagnetic wavelengths. Therefore, none of the carbon black, cold black, commercial copper oxide, ball-milled copper oxide, synthetic copper oxide, or copper oxide mixed with cobalt oxide used in the comparative samples can provide the balance of blackness and reflectivity in the near-infrared and lidar electromagnetic wavelength ranges obtained by the cobalt oxide coated with copper oxide disclosed and described herein.

[0128] Example 3 - Carbon black pigment coated with copper oxide

[0129] Copper oxide-coated carbon black pigment was produced by introducing (NH4)2CO3 as a precipitant into a solution containing Cu(NO3)2 and carbon black particles using a wet chemical method. The weight ratio of Cu(NO3)2 to carbon black was 1:3, and the molar ratio of Cu to carbon was 0.07. The precipitant was added until a precipitate was formed. The formed CuCO3 coated the carbon black particles. Then, (NH4)2NO3 was removed by washing the precipitate with water and ethanol. The solution was then filtered to obtain CuCO3-coated carbon black particles. The precipitate was dried at 120°C for 12 hours and then calcined at 300°C for 3 hours to form CuO-coated carbon black particles. Scanning electron microscopy (SEM) images of the resulting copper oxide-coated carbon black with a CuO:C ratio of 25:75 are shown below. Figure 12A middle. Figure 12B and Figure 12C The more detailed SEM images shown illustrate the antireflection moth-eye structure of carbon black coated with copper oxide at a CuO:C ratio of 25:75.

[0130] Compared to standard carbon black, cold black, commercial CuO, and a physical mixture of CuO and carbon black in a 25:75 ratio ( Figure 13 CuO mixed with C) and carbon black coated with CuO in a 25:75 ratio ( Figure 13 The lidar intensity of carbon black coated with copper oxide (CuO deposited on C) with a CuO:C ratio of 25:75, formed as described above, was measured. The lidar intensity was measured as described above after applying a transparent coating. The results of this test are shown in... Figure 13 In the middle. For example Figure 13 As shown, carbon black coated with CuO at a ratio of 25:75 exhibits significantly better lidar intensity than carbon black but less than that of cold black and commercial CuO. However, cold black and commercial CuO do not possess a blackness comparable to that of carbon black coated with CuO at a ratio of 25:75. Figure 4B As shown. Therefore, CuO-coated carbon black in a ratio of 25:75 provides a balance of significantly improved lidar intensity and blackness that cannot be achieved with any of carbon black, cold black, commercial CuO, or physical mixtures of CuO and carbon black.

[0131] Example 4

[0132] To verify the performance of the CuO-coated carbon black as disclosed in Example 3 in a dynamic environment, a robot (model TurtleBot 3 Burger) was equipped with a 905nm 2D laser scanner. The laser scanner is capable of 360-degree sensing, collecting a set of data around the robot for simultaneous localization and mapping (SLAM) and navigation, as well as for stopping upon obstacle detection. A coating panel was placed in front of the autonomous robot. When the panel was coated with carbon black, the robot collided with the obstacle without stopping. However, when the panel was coated with copper oxide-coated carbon black manufactured according to Example 3, the robot stopped before impacting the panel.

[0133] While specific embodiments have been shown and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Furthermore, although various aspects of the claimed subject matter have been described herein, these aspects need not be used in combination. Therefore, the appended claims are intended to cover all such changes and modifications within the scope of the claimed subject matter.

Claims

1. A copper oxide-coated pigment, comprising: Particles with an outer surface; and A copper oxide layer on the outer surface of the particle, wherein, The copper oxide-coated pigment has a reflectance of less than or equal to 5% for electromagnetic radiation in the visible spectrum. The copper oxide-coated pigment has a reflectivity of greater than or equal to 5% for electromagnetic radiation in the near-infrared and lidar spectra. The particles are selected from Co3O4 or carbon black, and Based on the total weight of the copper oxide coated particles, the copper oxide coated particles comprise a quantity of copper oxide greater than or equal to 1.0 wt% and less than or equal to 90.0 wt% and a quantity of carbon black or cobalt oxide greater than or equal to 10.0 wt% and less than or equal to 99.0 wt%.

2. The copper oxide coated pigment according to claim 1, wherein, The particles are Co3O4.

3. The copper oxide-coated pigment according to claim 1, wherein, The particles are carbon black.

4. The copper oxide coated pigment according to claim 1, wherein, The copper oxide-coated pigment has a reflectance of less than or equal to 2% for electromagnetic radiation in the visible spectrum.

5. The copper oxide coated pigment according to claim 1, wherein, The copper oxide-coated pigment has a reflectivity of 20% or higher for electromagnetic radiation in the near-infrared and lidar spectra.

6. The copper oxide coated pigment according to claim 1, wherein, The copper oxide-coated pigment has a reflectance of greater than or equal to 0.5% and less than or equal to 2% for electromagnetic radiation in the visible spectrum.

7. The copper oxide coated pigment according to claim 1, wherein, The copper oxide-coated pigment has a reflectivity of greater than or equal to 10% and less than or equal to 65% for electromagnetic radiation in the near-infrared and lidar spectra.

8. The copper oxide-coated pigment according to claim 1, wherein, The pigment coated with the copper oxide has a blackness greater than or equal to 150 and less than or equal to 165.

9. Coatings, which include: Coatings and adhesives; and At least one copper oxide coated pigment according to claim 1.

10. The coating according to claim 9, wherein, The coating has a color with a brightness of less than or equal to 40 in the CIELAB color space.

11. A vehicle, including a body panel coated with the paint of claim 9.

12. A method for forming copper oxide coated particles, comprising: A precipitant is combined with a solution containing copper nitrate and particles to form coated particles, wherein the particles are Co3O4 or carbon black. The particles are washed to obtain washed and coated particles; The washed coated particles are filtered to obtain filtered coated particles. The filtered coated particles are dried to obtain dried coated particles; and The dried coated particles are calcined to form copper oxide coated particles. The precipitant is selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate.

13. The method according to claim 12, wherein, The precipitant is ammonium carbonate.

14. The method according to claim 12, wherein, The particles are Co3O4.

15. The method according to claim 12, wherein, The particles are carbon black particles.

16. The method according to claim 12, wherein, The coated particles include particles coated with copper nitrate, particles coated with copper hydroxide, or particles coated with copper carbonate.

17. The method according to claim 12, wherein, Washing the coated particles involves washing them in a mixture of ethanol and water.

18. The method according to claim 14, wherein, Drying the filtered coated particles includes drying the filtered coated particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

19. The method according to claim 18, wherein, The calcination of the dried coated particles includes calcining the dried coated particles at a temperature of 430°C or higher and 470°C for a duration of 0.5 hours or higher and 5.0 hours or higher.

20. The method of claim 15, wherein, Drying the filtered coated particles includes drying the filtered coated particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 5 hours and less than or equal to 15 hours.

21. The method according to claim 20, wherein, The calcination of the dried coated particles includes calcining the dried coated particles at a temperature of 200°C or higher and 300°C for a duration of 0.5 hours or higher and 5.0 hours or higher.

22. A method for forming copper oxide coated cobalt oxide particles, comprising: Sodium carbonate precipitant is combined with a solution containing copper nitrate and cobalt nitrate to form coated cobalt oxide particles; The coated cobalt oxide particles are washed to obtain washed coated cobalt oxide particles. The washed coated cobalt oxide particles are filtered to obtain filtered coated cobalt oxide particles. The filtered coated cobalt oxide particles are dried to obtain dried coated cobalt oxide particles; and The dried coated cobalt oxide particles are calcined to form copper oxide coated cobalt oxide particles.

23. The method according to claim 22, wherein, The coated cobalt oxide particles include cobalt oxide coated with copper nitrate.

24. The method according to claim 22, wherein, Drying the filtered coated cobalt oxide particles includes drying the filtered coated cobalt oxide particles at a temperature greater than or equal to 100°C and less than or equal to 140°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

25. The method according to claim 22, wherein, The calcination of the dried coated cobalt oxide particles includes calcining the dried coated cobalt oxide particles at a temperature greater than or equal to 430°C and less than or equal to 470°C for a duration of greater than or equal to 0.5 hours and less than or equal to 5.0 hours.

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